Own domain questions
 

Being new and reading many posts, it's obvious having your own domain is the optimal solution to having control over your email (ownership, migration, desired local parts, etc.).

I really don't want a high maintenance project emailing recipients to ask them to whitelist me, or contacting admins for companies asking the same. I'd like the path of least resistance. The names I'm "meh" about that are available as .com and I'm not thrilled with them, but the ones I like are available as expensive .io or the inexpensive .xyz domain.

I've read from mostly several year old posts that new TLDs and new domains can generally be problematic (especially the "spammy" .xyz), even after SPF, DKIM and DMARC is up to spec. Are there still issues with having a new domain with a TLD such as .xyz, .io, etc?

If hosting a new domain at Fastmail, is there a better chance of minimal issues, since they'd be providing DNS service?

There is nothing especially protective about using FastMail. Using your own domain with an unusual tld is usually only a problem for a short initial period, especially if SPF and DMARC are correctly set up (which FastMail does make easy). Establishing your own domain, and establishing its trust is a one-time effort, and I suggest you bite the bullet and do it.You could register the domain, and initially use it only with a couple of correspondents you can warn to acknowledge messages you send them so you know of any issues. Once the domain has been in active use for a month or two, it is much less likely that receiving mail servers will flag your messages as suspicious, and you can extend its use to your other correspondents.