I often spin up a quick python http server. Just go to the folder which has the files you want to transfer and run the following command: python3 -m http.server. This will server the folder content Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) .... On your phone you can then browse to http://PC_IP:8000 and download what you want/need.

You could add encryption and authentication via ssh: https://guide.munin-monitoring.org/en/latest/example/transport/ssh.html or you could put it behind an nginx and wrap it in tls if you just want encryption.

Munin might be what you’re looking for. Very simple and easy to write your own plugins for if some information is missing.

http://munin-monitoring.org/