I can only recommend Logitech Unifying or Lightspeed devices here, both support firmware updates via fwupd and use encryption.
The G305 is an excellent mouse at a great price. And has Piper/libratbag support.
But you already have a Pro X which is Lightspeed and so is already an encrypted connection.
you ain’t gon be gamin over bluetooth
because HID is HID, an attacker could send keystrokes to open terminal and run scripts or arbitrary data to attempt kernel exploit.