Nix is interesting and fine if you are a solo developer with time to learn the details. I did try it briefly but find the learning curve of rtx is near zero - it does less than Nix but is very easy to adopt in a team. Compatible with asdf but faster and easier in some way, and actively developing.
Buying a domain that includes email would probably work, or just getting a less commonly used email service. Fastmail is good and has many alternative domains.