They are doing everything they can to discourage third party app development.
I'd say you're moving the goalpost. Other than the hostility the founder showed towards LibreSignal nearly 10 years ago now, can you source any evidence to support your claim?
Looks like I might be moving to Proton Pass after all! I'll give them some time to see what they do about this, but will happily give my money to someone else and migrate friends/family as well.