Setup was painful. Initially the app didn't work after installation. I tried giving permissions in system settings / accessibility but that didn't help. I tried to go back to the previous Logi Options and that said my mouse wasn't supported. LogiOptions+ complained the backend wasn't running and provided a purple footer with a 'click here to start' (with no obvious feedback you were clicking in the right place) but that didn't help.
It then got into a restart loop where every time it started it took focus in the middle of the screen, getting in the way of what I was working on.
After a reboot (when the previous LogiOptions looked like it still started) , the app now works. There didn't seem to be any request for a reboot or warning that it could be needed in the installation process.
Within the app there doesn't seem to be an option about checking if my mouse firmware is up to date, or updating LogiOptions+ itself