This is an idea that has been forming for a while and i think that this one kinda needs to be implemented (also might encourage people to play on high seas more) I know on console you have the option to enable crossplay (or at least be able to have pc players join your session on safer) this is sort of an addon/extension to that idea that I know is possible to do as I have seen it in other games (to a degree) and it comes in two parts
Control lock:
This would be an option on PC mainly (AFAIK you can only use controller on console) where it does what it says on the tin, it sets your preferred method of controlling the game, if implemented it would have 3 options, none (you can switch between kb/m and controller) keyboard and mouse, and controller. Say you set your input to controller, this will make it so that the only key on the keyboard you can press is the push to talk (if you have it enabled) or text chat (which will then allow you to type) this then leads into the other option
Play with my preferred controller only.
Another one that is pretty self explanatory this time can be done on both consoles and PC, a slight change to the current console version which is only allowing cross-play (again AFAIK) where you set it to yes and you only get people who use that controller method or no where you can get any players, now obviously you (rare) can either set it so that if your a controller player you cant team up with a kb/m player till they change input to kb/m or force the setting to no if the party has multiple input devices, with this setting set to yes you are unable to change input until you reload the session.
the reason i feel more people would play high seas if these options were in the game is based on the idea that your more likely to get the try hards/cheaters that no one likes to play with in high seas using keyboard and mouse, and you only really play controller if you are chill and want to relax