Keychron K4v2 with SonixQMK can be customized to anything you want. I daily it in Linux and windows. I game in Linux, and work in windows (bleh) but I still want Macro’s to pass the HID port on my KVM so I just build custom key codes.
Any of the QMK/VIA supported boards are great in linux, so find the layout, and style you want. The K series are the older ones and they require more effort to get QMK running since they run on the Sonix/Evision MCU.
As for mice, i have a Glorious D- because I have small hands, and its fine. I could control it with OpenRGB but I dont care enough and it gets messy with a KVM.