Check https://svalboard.com/. Personally this is next keyboard / mouse i’m going to try (I don’t have experience with it yet, however seems to have enough customization to accommodate any needs).
I saw azeron recommended previously, svalboard is definitely supported on linux (uses via)
I like my librem5 (hardware, feel etc). Software is obviously yet to catch up (from my perspective).
I just wish as a company they upgrade (forthcoming) their communication