Suggest Low cost roon endpoint that is not a raspberry pi

Yes, especially if you need to run Windows ASIO drivers for your DAC to do native DSD. While a lot have been patched, there are still older DACs which will not do native in Linux.

Album art yes (see @Saturn94 post above). But it’s not a replacement for a Roon remote although I think you can use it for minimal functionality as shown in the pic. I just use my iPhone as the remote and it works perfectly.

I use 4 pis on wifi and not one issue with any of them. I suspect the issue is your wifi setup and not the pis themselves perhaps focus on improving that, check your using the least congested channels, use 5GHz where you can, look to add more access points to spread the load as one can get bogged down very quickly if you have a lot of wifi devices in the home.

Agreed. USed squeezebox touch. £50 and a perfect roon endpoint

How about anything on this list:

I would probably use an old NUC, or Odroid.

Maybe a Pi Zero - with picoreplayer (Run the endpoint as a squeezelite endpoint. Pi Zero’s can still be purchased.

What about a Raspberry PI compute with mother board (Still available)