The easiest way to do this is through Tailscale. It is a super easy to set up Wireguard VPN Mesh that allows you to access your self-hosted services without exposing them to the public internet.

https://tailscale.com/

Here is a great article to get you started: https://tailscale.com/kb/1017/install

They also have an awesome YouTube channel with great tutorials to help you get started. https://www.youtube.com/@Tailscale

Note: while this way not directly answer OP’s specific question, I believe they will get the outcome they are looking for: external access to self-hosted services

+1 for this. I use and love Backblaze. Really affordable. ~$5/mo for unlimited attached external harddrives.