I can agree with this, at least.

Wouldn’t just using a temporary phone number service work? From what I remember, you just need to recieve a text message and put it into Signal during registration. From skimming through the post, there’s no mention of this option.

I would agree somewhat, except I think Bitwarden verifiably doesn’t store unencrypted password data. Of course, I think that a self-hosted solution is pretty much always more secure than one that isn’t, but the convenience Bitwarden provides is real.