Adding applications and rebuilding is generally trivial.
The problem becomes if you want to use flakes or home manager, which you probably should. The config for those is complicated and poorly documented.
I don't know the programming language. I've been running it for about a month now. If you're not doing anything complicated or doing any crazy conditionals or running one config for 27 boxes it's no different than editing a yaml.
It took me about 2 days to get Nvidia working properly with offloading that was my hardest task so far.