I'm not exactly sure what you're looking for with non-proprietary, open source artist music building platforms... maybe these two fit your bill. If not, they're open source, so you can definitely help make them fit your bill.
Dude, he had guy play the ocarina on the last Skirmish. It was hands down the best ocarina performance I've ever seen. You don't know how amazing these skirmishes are.
https://bunny.net?ref=pnx450l5qr
BunnyCDN lets you pay your hosting in Bitcoin. Use https://musicsideproject.com/ to create your RSS feed, add your value block to get paid in BTC, host it on Bunny and pay your hosting bill in BTC. It comes out to around $1 a month. No host gets to take their 10% cut of your sats, and you're not paying a host $6 - $20 per month to do something you're perfectly capable of it. Stop being a digital cuck and start taking responsibility for your own content.

Any musicians looking to self host your own Decentralized Music 2.0 feed, I've updated MSP to make it as easy as any hosting company. Walk through the tutorial for integrating Bunny CDN, and uploading your mp3s and art work is as easy as drag and drop.
I chose Bunny because it's cheap. I've been using it for a year, and I've never spent more than $1.10 a month.
Save yourself some money, and take sovereign control of distributing your own music.
musicsideproject.com
Once your on MSP, in the main menu, Log In.
Register a new account if you don't have one.
Once you're logged in, you'll see Bunny Credentials in the Main Menu. Click on that, and there's a tutorial for integrating Bunny for serving your files.
If anyone decides to try it out, let me know if there's any confusion in the tutorial.
And because I care about self-hosting and sovereignty, all of my code is open source. If you know what you're doing, you can just as easily run this on your own machine instead of relying on my website. This should hopefully lower any barriers to taking control of your own music feed.
github.com/thebells1111/msp-studio
Freedom isn't free
It costs folks like you and me
And if we don't all chip in
We'll never pay that bill
Freedom isn't free
No, there's a hefty fuckin' fee
And if you don't throw in your buck o' five
Who will?
LNBeats is for the people, ALL the people. Unlike some other lightning enabled music players, we don't believe in segregation. EVERYONE is allowed to swim in our pool.
Open Source Decentralized Music Player for EVERYONE
Here's an even better link for LNBeats, the only real OPEN bitcoin music player. No walled gardens, everyone is allowed to swim in this pool.
One of the things that pisses me off is a lot of people seem like they don't actually want to disrupt the system, they just want to be the ones running the system. Disrupting the system means an actual change in mindset, not a change in who the slaver is. "Meet the new boss, same as the old boss"
The people that see v4v as all about money are basically prostitutes. I'll give you a service, but I'm expecting some money in exchange. A girl has to eat you know.
I see v4v as a friendship. I help her move, she makes me dinner, I change her tire, she drives me to my surgery. We're providing valuable things to each other that we would normally have to pay for, we're exchanging value, but we're not worried about who's providing more or what's fair because we actually like each other.
I'd rather have sex with a lover than a hooker.
v4v is transactional, but not in the same way of setting prices and telling the person "take it or leave it". That's the transactional nature of something like an employee/employer relationship, "Here's some work, now pay me my agreed upon wage". No, it's transactional like a marriage. A husband takes care of his wife because he loves her, not because he gets something out of her, and she returns the love in kind. It's an exchange of value, but one built on love, not negotiation.