I don't have much issues with Bluetooth in Linux, works just fine on my Kodi installs, audio, remotes the whole kit. But I can recommends the G60S Pro remote. It has both 2.4Ghz and Bluetooth so you don't have to rely on the Bluetooth if you don't want to. Flip it and it has a keyboard, incredibly useful!

Before that I ran CEC remotes (found is kind of meh), IR receiver (worked fine enough), and other 2.4Ghz remotes (MX3 variants, including a Bluetooth one).

I also use the companion phone app, Kore, on a Android.

Like others here I've been running Kodi for nearly 20 years, has amazing spousal approval rate. I just redid my setup, PXE boot a couple of Pis and an x86_64 machine (and Qemu for testing) it's a bit of a pain to share more than the libraries (my MySQL), but that's really more than most people want anyway (and I did manage to share almost everything with some NFS trickery, advance config path substitution, bind mounts, etc).

This is the way.

I use I think this one: http://www.riitek.com/product/254.html

It has orange buttons that you program to the TV (I have on/off, volume, and changing input source) then the white buttons and the direction pad to move around and play things in Kodi.

If you don't want to rely on Bluetooth, there are lots of keyboards, mice, and media remotes with dedicated dongles.

I use one of these, for example: https://www.amazon.com/gp/aw/d/B07ZKL66GY

Get a mini PC with an intel n100 and get a flirc remote adapter. Low power, quiet and plays 4k content perfectly in Kodi

The bare minimum viable is an AMD CPU of some description, and an AMD GPU that can at the very least decode h.264 and h.265; an FX-4300 or R3 4100+RX 550 combo would be a good example for the bare minimum viable Linux HTPC build, as Polaris cards like the RX 550 can decode h.264 and h.265.

Ideally, you'd have an AMD CPU and an AMD GPU or integrated graphics in the case of an APU, that in addition to decoding h.264 and h.265, can also at least decode VP9 if not also AV1; an R5 3400G would be a decent HTPC APU in that case since Vega integrated can decode VP9 in addition to h.264 and h.265.

Beyond the hardware, set up the appropriate hardware acceleration so you can decode video through VA-API, and then set up Kodi and get a cheap tablet to install Kore on and use that for a remote.

this may seem weird, but steam bigpicture mode is great for a tv. you can make webapps for stuff like netflix, youtube, whatever with google chrome. 

i think kde has/had a big mode for tvs, not sure if its still developed. never used it bc i dont much like kde.