[Screams internally]

I use one of the “new” gtld domains for email. It works and I pay for a provider to do all the heavy lifting like your case, but you would have to configure DMARC, DKIM and SPF for your own domain. The big problem isn’t the technical part. It’s the clueless people who can’t imagine anyone not having a gmail address (the “why can’t you just have a normal gmail like everyone else” crowd). Some retail and government sites also flat out refuse email addresses that don’t end in traditional tlds (.com, .net, etc) or the country-specific tld. In the end, I ended up creating a gmail address for those morons which redirects to my inbox after months of struggling.

It’s the same with linux distros. One of the instances could get a critical mass of newbies but we will still have die-hards trying to gatekeep the entire fediverse.