Earlier quoted context omitted.
If you get your own domain, get one on a well-known TLD (e.g. .com, .org or your own country code). If you get a gTLD that's not well-known, there are some endpoints that will block you because your email is "not valid".
Is .dev or .io considered a well-known gTLD by now? I’m in process of setting up email for my .dev domain.
That said, there are ccTLDs which behave more like gTLDs (like .io, .me, .fm, .gg, .cd) and are treated as such across much of what you do online, but whether that'll impact your email delivery depends on who you communicate with and how they treat spam.