first@last.com would be ideal, I use first@firstlast.com, but that wont be good for sharing. I would stick to a common TLD at least (.com, .net, .org, or a country) for deliverability.

Check out Lunanode. Cheapest option is 3.50 a month and bonus points for being Canadian. I just recently set my VPS up there and am really pleased with them. Afaik they support your needs including custom ISO.

If its a mission critical use, I would stick to a more common TLD (com, org, net, etc). Country TLDs should be okay too.

What I do to keep DNS consistent inside and out is use Tailscale on all my clients. I host a DNS server hosted on my tailnet that is set up as split DNS for my “kickassdomain.org”.

Fwiw I switched from k3s to Talos and find it much easier to manage. I run 3 mini 1L PCs with rook-ceph and it works flawlessly even on 1Gbe.

I quite like Fastmail. It’s a bit expensive but the service is very reliable and they have a well established reputation. You can create masked emails using their domain or your own from the web interface.