Portable Speaker?

No

They have the 1, 3, 5 and Playbar for TV sound.

The Play 1 could be considered portable but it doesn't have a battery and doesn't claim weatherproof.

Sonos won't pre-advertise any product intentions but the consensus is that a battery powered Sonos speaker is highly unlikely

Too bad. I think there would be a market for that among the Sonos community. I understand that they operate on a wireless platform (as opposed to Bluetooth - so you couldn't take it to the beach), but it would be nice to have the freedom to utilize a speaker in your garden, shed, backyard - anywhere within range of your home wifi signal.

But if it's in range of the home Wi-Fi it's in range of a power extension cable. I'd be surprised if Sonos produce a portable speaker.

I suppose that's true. But wires and cables so darn clunky!

Connect:Amp (safely tucked away inside the dry home)
+Outdoor speakers of choice
+Speaker wire
--------------------------------------------------------
Phenomenal listening experience

Consider doing what I have done - a good quality weather proof bluetooth speaker, an old out of use 32gb iPod touch loaded with all my favourite playlists. Once past that one time investment of time and relatively little money, music on the go wherever you can go in whatever weather you can take. Sound quality that is very acceptable and a solution that I don't see Sonos offering, so this workaround is very useful to me in spite of having permanently installed outdoor speakers that are Sonos fed.

I have to agree that a nice, high quality, rechargeable Sonos speaker that's about the size of a Play 1 would be amazing. I cannot imagine why they would not already have this in development. It's absurd to run an extension cord into the yard or gardening shed or to have an electrician install a plug in just the right spot on our deck simply to power one speaker once in a while... I can't imagine why Sonos would snub their nose at this opportunity to truly become "wireless"..

I would also thank Sonos if they take that step; I have several speakers in my system (including the CONNECT-AMP+wire+outdoor speakers in the garden solution 😃 ) but I think a portable, rechargeable speaker (if possible, smaller than PLAY-1) would cover some of my needs (ie. shower, occasional work in the garage...). I would not prioritise sound quality in this particular speaker, but I would love to have it integrated with the rest of my system!!

Until the time Sonos gets around to doing this - if they ever will - the easy availability of music via streaming services means that these needs can be met right away by one of the many and now quite decent sounding bluetooth weatherproof portable speakers available. It can then be just as easily used on the road, out of range of Wifi or mains power, with music downloaded to the phone for such listening.

Every time I talk to a client about Sonos this comes up. Every. Single. Time.

It's just expected, and both a surprise and a disappointment to them that it's missing from the range.

Yes, as an installer I can work around this in various ways, but that still doesn't change the fact that from a new client's perspective they don't understand why something so good indoors hasn't made the short step to outdoor entertainment. An equivalent to the Arcam rCube but with Sons Wi-Fi and back-up Bluetooth is such an obvious product.

Did this with a connect plus retired receiver. Worked nicely as I'm able to run 4 speakers outdoors without the concern of outdoor power cords.

Yes, as an installer I can work around this in various ways
My guess is that people like you using Sonos products are a very small part of their target market. While the adjacent portable bluetooth speaker market that is large, well supplied at price points from USD 20 to USD 500+ and is fiercely competitive has a solution that works just as well for the much larger majority of even Sonos users that have a smartphone/pad and subscribe to streaming services - who are all clamouring too loudly for Alexa features at this time to allow Sonos the luxury of resources to divert into that game.

An equivalent to the Arcam rCube
That this is now obsolete and something no one that knows the present portable speaker market will want to buy and carry around shows what a challenging/dynamic environment this market is.
People can now get - and therefore want - speakers that will float in the pool with them, with battery lives of at least 10+ hours. And those that aren't a weight to move around. Sound quality is usually just acceptable but loud/bass heavy enough, and in that market it is more about features and usability since the environment itself doesn't require or support much better.

Brilliant, I love it. That's my work around for the bathroom until the boffins at Sonos come up with a better solution.
(not water soluble!!).

I think that many Sonos users have a Bluetooth portable speaker, and a lower quality is acceptable for outdoor use, but the request of a device like this by Sonos it’s not so absurd because it could be another speaker (integrated with Sonos system) that u have when you come back home and that can be easily moved if you need from one room to another one where you don’t have a speaker (bathroom, kitchen...). So it can work via Bluetooth (but wi-fi too) as a stand-alone speaker and with its integrated battery when you move it temporarily in the bathroom for a shower, or in the garden, working with the whole Sonos system in your home

Every time we have a big party in our garden (or actually I do anything in the garden) it annoys the hell out of me that there's still no battery-powered Sonos.

SONOS recently announced (coming soon) outdoor speakers - https://www.sonos.com/en-us/shop/outdoor-speaker-pair.html

Note that these speakers are not Sonos speakers, but are from a company called Sonance, which Sonos is doing some co-marketing with.