I have used proton mail for sometime but there are some very annoying features. Like if you do not login in the account for 20-30 days, email account is deactivated. I am not sure if they have same kind of policy for this wallet but if they need me to login frequently to keep the wallet active, I do not even want to tet them at all.
That's for the free account, I think. I don't think the wallet was designed for those kind of users given those policies. They could have unforeseen consequences. For example, what if a user's account gets deactivated but they have bitcoin in their wallet? Sure, it's non-custodial and you can get the mnemonic phrase, but will you be allowed to access such a thing if your account is suspended?
These are the questions that need answering.