Now, this won't really be an answer but more my general thoughts:

I was in a similar situation as you, wondering about this when trying to buy my first turntable and have it work with Sonos.

I decided to go with the Victrola Onyx (color preference over the Carbon or Pearl), and I can't speak for the unreliability other than occasional "handshake" issues with Sonos speakers. This is unfortunate, and I can't really say this is a Victrola issue; it just might be. (Another note is that this sync issue only applies to my stereo pair of Era 100s in my office; I've never had an issue with my Arc. It could be a Sonos issue with how they expose a stereo pair. As I write this, I'm actually using them and everything is great after maybe clicking the volume up on one of the speakers to wake them, which is odd since they're constantly powered).

From speaking with Victrola support on a separate issue, it seems like everyone is scrambling to understand Sonos' app changes and issues they've been pushing on the app. It sounded like even with the Works with Sonos partnership or badge, even Victrola will suffer from Sonos' updates.

What it does do is stream excellently once the turntable "syncs up" with the speaker group it's streaming to. I have it run on the lossless option in the settings and can't say I hear any quality issues. It picks up old used records' pops, cracks, and hums, and plays new records flawlessly. I am very happy with the purchase and for the most part, everything just works. Besides that sync issue, as I'm flipping or changing records, everything plays as expected without any connectivity drops or quality drops. (As mentioned earlier, I think it's a Sonos wake issue). I'm really happy with it and would recommend using the "saved" money going with Victrola to get an AT-VM95ML stylus (AT stylus as the Onyx comes with an AT-VM95E). It really improved the sound quality and soundstage.

Like mentioned, once streaming, it is perfect for me. I can hold the pause button on my other Sonos speakers that aren't streaming and they group as expected, and everything sounds as expected on each added speaker. Great product overall. The dust cover leaves a lot to be desired, but oh well.

Another thing is that I went with the Victrola from a money allocation thought. The Project T2-W looks to just be a wireless option of the T2, which seems like a good turntable at about $500, but spending double, maybe more, to add wireless, I would rather use that price range to buy a better turntable and an Era 100 to line in and stream the turntable that way than spend all of that on a T2-W. In a similar price range are the Victrola Streams, and those only require one cable, one device, and look to be of reasonable quality.

So in my head, a $450 (the price I got it) Victrola with Sonos connectivity is about a $300-$400 valued turntable (based on their Onyx Hi-Res line). Or a $1200 T2-W with Sonos connectivity, which is about a $550 valued turntable without a preamp. Or a strictly focused analog turntable with a preamp valued at a desired amount of quality + a $150 Sonos Era 100 (current refurbished sale price on Sonos). I just weighed the pros and cons there.

I would still love to get an answer to your question: why did Project say wifi is unreliable? Why are the Victrola turntables not showing the same issue? Could it be that Works with Sonos certification and partnership?