This is pretty much how I’m hosting a similar set of services to you. I have a couple of dirt cheap VPSs ($10/yr via racknerd) which serve as public access points. One provides a wireguard tunnel and port forwarding to a mailinabox instance serving mail for my various domains, the other runs a wireguard tunnel and nginx reverse proxy for all my public-facing services. A little fiddly to set up the port forwarding, but it’s been rock solid since I set it up.

Re: email, it’s not too hard, but it is unforgiving. Mailinabox makes it much, much easier to set up an email server that doesn’t automatically go to spam. Basically though, if you have your SPF, DKIM, DMARC and RDNS set up correctly, your golden. Mailinabox takes care of all of it except RDNS.