Safely exposing services to the Internet (opens in new tab)

Hi all, I’m looking at exposing some self-hosted web-based services externally so that some relatives can access them and would appreciate some advice. Vikunja is the starting point (mostly to facilitate my spouse and I using it when away from home) but in future I want to set up Immich or similar to replace Google Photos, and that in particular will need to be shared with friends and family (especially so that immediate family can have camera uploads on automatically). I understand that idea...