I found that the most simplicity way of doing it if you want remote acess otherwise you can connect locally without tailscale
Totally understandable, however basic tailscale version is free and you can just have that installed on all of the connected devices as a “reverse proxy”. You then use the ip adress from the server or main computer with the files and connect to its tailscale provided ip adress after turning it on and as long as you have port 8096 open on the server computer (http:/with your adress here:8096) you can connect to the server through the jellyfin app on the device you’ve installed it on.
RunnerUp is an app ive been using for a while and it does the basic gps tracking for your activities and even has an option to tell you if your pace is slower or faster than you set. You can connect it to your Strava account to upload data to if you want, but otherwise the data is on your device. I don’t know about smartwatch compatibility, but I use the phone app and just put my phone in my Nathan’s Belt.