About MacOS and iOS Apps.
Mail application should be done for MacOS operating system and dark theme should come for iOS mail application.
In addition, as a suggestion other than these; free mail data storage space can be better than 500 MB.
Doesn’t the paid tier support IMAP? Couldn’t you then use the mail app on MacOS?
OMG - I am so sick of ProtonMail in a browser on a MAC - drives me nuts. Before I start down the bridge path with Thunderbird or similar is there ANY chance you are going to bring out your own native app?