hemce, in your case, you trained for a job which is something you do to get money.
if you want to write an app, go lool up guides or classes on the type of app you want to write. not everyone takes said class because it may be irrelevant to their field of programming.
the only thing they will typically all share is basic understanding of variables and object oriented programming.
i wouldnt say im an expert at it as ive only had my media server for a month now, but how i approached making it user friendly was buying a domain name, and using a cloudflare tunnel to link your ip addresses/port to a subdomain.domain combination.
e.g i have overseer accessible by overseerr.domainname.extention and have it linked to the servers ipadress and port number. if i wanted to add another one, i would for example add a new subdomain and do the same (e.g plex.domainname.extention and point it to the correct ip/port combo)
although this has the cost of owning a domain, it doesnt require you to open a port so its better for security reasons