What do they offer?? An alternative to email that isn’t standard, not based in open and standard protocols like IMAP/SMPT at all and is incompatible with everything else out there that FYI is distributed. So this is basically another attempt at emulating Proton’s success and making email effetely less standardized. lol
The spreadsheet is very opinionated for eg. Proton fails in integration very hard because you can’t use it with a generic email client without extra steps… and in some platforms like iOS your only way to use it is by using their own app.