I too need to learn this but haven’t had the time. I’m currently exposing my public IP and forwarding some ports which I want to avoid. I believe Cloudfare tunnels and/or reverse proxy using nginx or something is the solution. I am much of a noob myself so I barely understand it all, have just managed with google searches, guides, and trial & error so far. Here’s a guide I found which I’ll be trying out soon and searching more in that direction - https://programmingpercy.tech/blog/free-secure-self-hosting-using-cloudflare-tunnels/

Sorry I’m still learning Lemmy and don’t know how to edit my comment, I didn’t realise this post was on foss, so for a shared drive Nextcloud could be a better option than Mega

Linux (Ubuntu could be a good start), own NAS drive or a service like Mega for a shared drive, and Protonmail/Tutanota could be good options. There are probably more online shared drives you could look for if you don’t want to use Mega.