I have this one, acts like a mouse (gyroscope) and keyboard (arrows, back, home, vol+- on the front side, almost-full qwerty on the back).

https://www.aliexpress.com/item/1005006860823468.html

My suggestion would be an airmouse remote, possibly with an built-in keyboard. This is because sooner or later you will want to use a web browser to stream content, and a mouse is incredibly convenient for that.

There are many bluetooth remotes you can use for this. You may want one that has a built-in keyboard, or just one with arrows and a handful of buttons.

This is listed on the linked page. KDE makes the excellent KDE Connect. You can also use a TV remote, game controller, or keyboard and mouse.

I use kde connect with my android for my htpc. Works nicely enough on stoxk kde.

Unified Remote with my phone https://www.unifiedremote.com/

Look up "USB RF remote" on eBay. There are two common ones you'll see everywhere. I have one for my Kodi system.

If your HTPC supports HDMI-CEC, it will just pass-through the inputs from the TV remote, no additional ones required.

I use KDE connect, it has a really nice remote input feature.