Isn't there built-in Encryption (point-to-point IIRC). I remember Proton being big on security in that regard (before Gmail copied it anyway).

In any case, I hate how Gmail has turned off making burners to where you need a phone number and other shit that wasn't needed back in the day. I dunno if a law/"child protection" act caused it, but it sucks because that was my main way of doing throwaways. Create a g-mail account in like two minutes and then just use the +/. trick until needing a new one.