Samba.

Or one time I made my own simple file sharing website

It probably isn’t going to cost less to get something without wifi.

Keep stuff that’s not designed to be exposed to the internet on your LAN behind your router’s firewall.

Use a VPN to access your LAN remotely. Tailscale is the easiest way to do this, but I found it not too hard to set up WireGuard.

I just selfhost bare git repos on an ssh server