Ideally let us configure it per login item, or choose when selecting to autofill.

For example, a checkbox to select if username+password or email+email will be autofilled.

Many sites don't accept username at login, but it is still the default when autofilling.

It seems like Proton Pass will just use the username instead of the email no matter what, and you can't disable or change preference once it's populated, the only way is to basically delete it and add it to the notes or hidden text. My usecase would be to just have the username there just in case if it's needed and be able to choose which to prefer/prioritize. Sometimes some services will base accounts, security and support on the username (steam, ubisoft) more than they would on the email address, but they still require email (or both) for login.

Not all sites you log into require an email address just a username Proton pass will not allow you to create a username only login. And will only 'psste' from the email address field

Currently you can only store emails in credentials objekt.
Some services require an username instead of email address to login and you are not able to store the username in the email field because of the email validation.

Would be awesome so be able to store both (email and username) or just one of both.

There is a problem right here in uservoice, the firefox Pass extension detects the field as a username, but the website requires an email address.

Maybe I'm missing something but the only way to get around this is the manual approach of going inside the PASS extension or webapp, navigating to the specific Login entry, copying the appropriate field value there, and manually pasting it into the website's textbox.

It may be an extension bug, a misdetection or rather a misconfiguration of the website, in that case it may be nothing else Proton could do other than to appeal to webmasters to try to respect/standardize authentication fields for password manager compatability.

Additionally, in each of the login entry, there could be an option to select priority over which gets automatically used when filling or auto-filling, for example roughly "Prefer Username When Auto Filling" or "Override / Swap Email / Username values for misconfigured fields" or something.

Thanks

(Side note: I've also noticed that while password fields do get filled properly, the proton icon isn't being displayed in most cases, I think there was a change, I've seen it more regularly, now I see it rarely.)