No need to put homelab in quotes, it’s whatever is your lab. We all have different setups that grow and shrink as we learn.

Let me show you a smaller option than a full rack amp. I used this exact setup before except using an AirPort Express instead of the pi.

I would do the Pi (your plan) -> this -> bookshelf speakers like these.

Does everything have to be all in one, or are you open to exploring passive speakers and a receiver?

Since this is in Homelab, I’m assuming you have access to a 19” rack. You could rack mount any amplifier (I like crown amps personally) and then feed either a Bluetooth or Raspberry Pi using a line/headphone amp. That also gives you the ability to continuing adding amps to feed more speakers around the house. That’s my homelab answer.

Home theater answer would be to look at a home theater receiver.

We just turn them sideways on a shelf at work. We use a lot of micro form factor and they look slick in a row on a 1u shelf. We fit 3 or 4 (can’t remember) wide across 6 shelves.