I normally try and do "fun" work. This largely depends on how autonomous your job is. I was a PhD student doing research for a company and I received very little oversight for 3 years.
The supervision I did receive was great though. They understood needing to take a break and slow down. At those point I would generally read papers, watch PyData talks (highly recommend them, like inspirational ted talks for data people), or contribute to open source to learn about new tools or design paradigms.
Welp. This is me. I spent a few hours debugging a failing test that was caused by a package update. If only I checked the changelogs...
I interviewed for a position that I was comfortably qualified for. As soon as they mentioned a 3 hour whiteboard interview in person I politely hung up the zoom call.
On the flip side, I had a company give the best interview process of all time. They told you how many people were remaining in the rounds. The programming task was to implement a hugging face model as a FastAPI. There was also a short video interview that took 5 minutes if you had basic ML knowledge. Likely took 1-2 hours tops and it was actually fun.
I started using poetry on a research project and was blown away at how good it is. Next week I start a new job and I am hoping it is the standard.
Depending on what config data you need it might be a good idea to use environment variables. If all you need are server locations and credentials then environment variables are likely your best bet.
If you need fancy JSON or something else, global variables are nice.