PiKVM: force 1080p (or any mode you want) by editing the EDID
rw; kvmd-edidconf –import-preset=v3.1080p-by-default –apply; ro; then reboot the host (or replug the HDMI) so it re-reads the EDID. On V4 Mini/Plus none of this is needed: they already do 1080p60.