About tumbleweed/SLE:
OpenSuse Leap/SLE is probably the safer and less maintenance prone solution for a professional setting, but if hardware support is only available for Tumbleweed that is usually fine too (I am on tumbleweed on my work computer for 3 yrs now).
File access:
Your work desktop has to be exposed to the internet or you have to have a third server exposed to the internet. The server can be as minimal as a raspberry pi. For file access from other linux machines I use sshfs. If your desktop is behind a firewall, you would have to establish an ssh connection to the third server with a reverse proxy connection.
Ssh is not an option under android. I use a nextcloud docker instance to access files from android in a dropbox-like fashing (a certain folder is shared and synced across devices). Setting this is up is much more involved than the simple ssh access and a server of at least a celeron-type processor is recommended (which could be your desktop).
Often file access is even unwanted on Android, rather desktop access. I have used guacomole (again a docker based solution) for this which allows VNC access to your desktop from any browser. Again, this requires some effort to set up.