So, you are trying to join a federated social network. But, you feel that providing an email (literally the first federated social network on the internet) is a burden ? And you feel this is a burden because you don't want to give up a phone number to get an email account.
I believe protonmail has a free tier, and doesn't ask for a phone number:
And you can also pay for the premium tier with bitcoin.
https://protonmail.com/support/knowledge-base/paying-with-bi...
So hopefully that gets you out of a pickle where you want to have an email while maximizing privacy.
Second, protonmail requires a phone or credit card to sign up(wasn't the case before). You can pay for protonmail using btc and i was lucky to have an account before their sms verification requirement but I don't wish to use that address.
Third, why the hell do I need an email address to join any service? I can list many reasons why I don't want to use email ,privacy being only one small reason. Let go of email and sms,please! I emplore you, so much is at stake! You can use email all you want but free your users from needing it.
Why do I need an email for mastodon? Why???? It's literally a communication platform you can send me messages on? You can make a backup email (or backup mastodon account) for recovery although there are more secure options? Why do you insist on demanding people depend on a technology from the early 1980s to use new technology today? Why do I need burner phones and bitcoin wallets fudned using cash to join a free federated service? I use to be able to join an irc network,forums or even email itself without everyone and their mother knowing my phone,address, work place,associates,demographic info,etc...
Why can't you give it a break?
I understand your frustration from a privacy perspective. But I did not create mastodon. You may want to submit an issue on mastodon's github to ask for a non-email registration setting, and make your case why its important for privacy.
https://github.com/tootsuite/mastodon
But I also want to say that you are an outlier of the average user on the internet (most of whom have an e-mail address). I am sure that the guy who created mastodon, didn't add e-mail in the registration out of spite for privacy. He was following a common patter for registrations that works for 95% of people on the internet.
Going back to the discussion of creating anonymous email address. I didn't know that proton mail requires phone number (haven't used it before, just heard good things about it). I did not realize the state of email registrations across the web (haven't had create a new email account in a while). Your last option would be to just use those throw away email services, that generate a random email address, and let you receive some emails on that address.
Here is an example: https://temp-mail.org/