is there a way to play to Sonos 1 music stored on my Android phone

Not any longer, Google has blocked that, much like Apple did several years ago. You could copy the music to your PC, though, and play it from there. 

Don’t know for how long this will work in future, but if you’re still on a S1 system, „on this device“ still works with an Android phone. 

@g2c 

Perhaps just use the iBroadcast service on Sonos to play your tracks instead. See this link…

https://support.sonos.com/en-us/services/ibroadcast

Thanks, I have s2🤔

Thanks! i installed ibroadcast created an account, authorized sonos and now i have in browse: sonos radio, TuneIn and Ibroadcast. Ibradcast installed sample albums that do play on my play1  BUT i don't know how to add phone's music folders. Any help would be appreciated ☺️

See FAQ here for how to upload your tracks and just like the sample albums, your music tracks/albums will playback all for free too…

https://ibroadcast.com/faq/

Great! Thank you

I want to thank all of you who took the time to reply. Indeed Ibroadcast does allow, once the music is uploaded to their cloud, to play it locally on devices logged to my account and to play to sonos. 

Unfortunately, my file structure (nainly per composer) is not maintained and i may need to retag all album names.

Thanks again

If you are going down the retag route I can recommend mp3tag, works with other file types. I used it to embed album are and tidy my collection. 

@g2c 

To avoid work and to use your music directly as it is on your android phone, I would buy a Sonos speaker that supports bluetooth. With that you can play your music in the bt enabled speaker and also via grouping on all other rooms in your system. This will work with Sonos Roam, Move 2 and both Era models. 

Thanks, indeed i have a charge4 in in the upper bathroom but this gnd Sonos is a gift and i insist on using it😺

Access your own music from the Sonos App by storing it on a USB stick connected to your BT or Fritz router even if your computer is turned off.
This is my own experience in the UK, it should work for any router that has a USB port. I put it here in case it saves someone all the grief I suffered finding it out. I cannot give individual help and 5 minutes after I post it Sonos might change something. 

Change the name of your USB stick to something short and simple. Do not name it "music", or name any folder on the stick "music", as this can cause problems. The stick must be formatted as NTFS. Put all your album/artist folders and/or any individual tracks straight on the USB stick, not inside one overall folder. Do not put sensitive information on the USB stick as it may be visible by anyone who has access to your network.

If you have a windows computer I found it much easier to do all this on the windows app that can be downloaded from the Sonos website, rather than the app on my mobile.
In the Windows app click "Manage" choose "Music Library Settings" choose "Music Library" and you will see a window with a list of music folders, if you have any set up. Click "Add" and choose "Another folder or a drive connected to my computer". You might be able to "Browse" to the right place. If not, follow the instructions in the next paragraph starting at "type the address and name of the USB port".

In the Sonos app (on your mobile device) click the settings icon and choose “System” then “Music Library”, then “Music Library Setup”, then “Add Shared Music Folder”.
In “Add New Share” type the address and name of the USB port. For BT Smart Hub routers it is "\\192.168.1.254\usb1" where 192.168.1.254 is the address of the router and usb1 is the name of the port. It takes a few minutes to configure itself, do not click anything until it has finished. If it doesn’t work, try again and wait longer. The address and the name of the port will be different for other routers. 

Access the music on the Sonos android app by tapping the music icon, which takes you to “Browse”, choose “Music Library”, choose “Folders” then “\\192.168.1.254\usb1” (or the address you used). This takes me to my named artist folders, with the albums inside each.

For the FRITZ!Box 7530 AX router the address to access the USB stick is "\\YourRouterName\YourRouterName\YourUSBstickName" - Yes, the router name goes in twice. This will not work if you have enabled "USB remote connection".
 

Sonos isn’t changing anything.  A local music library on a PC/Mac or NAS (which is what a USB stick on a router actually is) was the very first way Sonos accessed music, predating music services, not to mention smart phones, by many years.