https://support.google.com/youtubemusic/answer/9716522?hl=en
Put it on an old computer / raspberry pi in a closet, or on a cloud VM. Domain name is <=$12/yr and many providers let you do DDNS via their API.
By the way, no landing page for the moment, I just bought the domain yesterday(musicbucket.cloud)
Not free, but Apple Music allows you to do that. I believe Spotify has that feature as well.
I have two different and excellent apps on iOS but there are Android apps too.
I would not hold your breath for this. The holdover MP3 collector is such a small minority that no mainstream company is going to consider them from here on out.
> is there any other free service where I could upload my MP3 collection to
If there was, why would you waste your time? Either it's not going to be free or it's going to disappear.
GPM was nice in that it merged the cloud music with your own collection, but I'm pretty resigned to the fact that I'm going to lose that functionality when they finally shut it down.
For Spotify, Google, Amazon, Apple, etc. that's not a problem.
Are people going to cancel their accounts because they can't listen to a very small subset of music? Probably but it's going to be a tiny minority of users that's inconsequential to their bottom line.
There had been murmurs for a long time of Google Play Music going away, so I moved off ASAP. Looks like that was a good call.
If not, is there any other free service where I could upload my MP3 collection to, with an app for mobile which would sync the data between mobile devices?
On Youtube Google nags me since months (a year?) to switch to Youtube Music but I get less service there. I fear the moment I hastily tap to try and loose Google Music.