Affordable or Custom-made multi-room audio setup (Bluetooth input and at least "Soundcore Rave 3" quality)

Hi everyone!

I already have a nice audio setup for my home office and my home theater, but I find myself carrying my big Soundcore Rave 3 speaker around for when I want loud music in a particular room (kitchen, garage, bedroom, etc.).

I don't know it this particular speaker is considered "good", but I personally like that it can easily fill up the room and has pretty good bass (listening to pretty much all kinds of music, but mainly electronic).

I would like to have this sound in 3-4+ additional rooms and am looking at options.

I thought about Sonos, but I find their speaker a bit on the expensive side for what they do.

Also, having a simple Bluetooth input available would be great for when I have guests over and they can just pair and be done with it.

I am comfortable with making the multi-room bit (probably with SBCs, amps and some Linux services) but would love to hear if anyone has found a good solution/setup for this use-case.

Budget-wise, I would like to stay well below 2k CAD ( 1250 EUR ?) but I'm open to any suggestion as I can see this as home improvement. I know at this price I could buy a bunch more of Rave3, but there would not be any multi-room features and I think it would look weird to have those speakers around...

Thanks!