I’ve always been passionate about it, so I would like to get a decent minimal knowledge on astrophysics, maybe to get into (amatorial) computational astrophysics.
Armchair astrophysics lover here. FWIW: I've always felt like PBS Space Time on youtube is one step short of a bachelors in astrophysics, at least, it's very good for picking up the abstract ideas around many of the major principles and then you can go research them deeper via reading papers.
Well, originally astrophysics involved staring at the sky for long periods and coming up with hypotheticals and maybe even theories about the movement of celestial bodies? it was very inexpensive and led to the fame of people like Galileo. Later, staring at the night sky was eclipsed a little. Folks like Gerard P. Kuiper used telescopes and made more detailed observations. The feild then rapidly became more complicated, but staring at the sky and eventually mastering the skill of designing and building your own detectors (what we in the feild refer to as "remote sensing") remains a proven method.
Search youtube for the theoretical minimum https://youtu.be/iJfw6lDlTuA its a whole playlist for quantum mechanics, Wilberger also has videos on hyperbolic geometry and relativity
It's hard to know what your current knowledge level is without more information, but it sounds like you're trying to develop a good background more just to dive into areas that seem fun to explore as a hobby, rather than focused study-- so I'm suggesting things that lead to more exploration.
A few of the resources below are good backgrounds, and Wikipedia is great for filling in your knowledge. Then to find interesting things to spark your hobby interest, I'd recommend following astronomers and astrophysicists on twitter, which will also help point you to interesting papers (which may take a lot of referencing Wikipedia to understand).
You'll need at least a little quantum physics to have some things make sense, so it's worth getting that from some of the links people mentioned below if you don't already.
Some twitter folks for key topics (and you can find interesting papers and other twitter folks from there):
@badastronomer (great for pointers/explanations for lots of topics)
@astrokatie (cosmology)
@nasaSun (the Sun)
@jannaLevin (black holes, gravity astronomy)
@matt_of_earth (host of PBS Spacetime, which someone else mentioned)
@ajpizzuto (neutrino astronomy)
I'm glad that was helpful. I'm in a similar boat of just being interested in this for fun. I have a little more of the math and physics background for it, but it's pretty rusty and I don't need it to understand even most of the interesting papers.
You probably want to understand three areas in more detail than you'll get from the wikipedia links I sent:
1) cosmology (people gave several good recommendations already)
2) wrap your head around the weirdness of quantum physics. I really enjoyed Six Impossible Things by John Gribbin as a good intro to different equivalent ways of conceptualizing quantum physics. It's not heavy on math and you can do it as an audiobook without missing anything.
3) Standard Model of forces/particles. It's really helpful to do this as a part of a book or long article instead of just wikipedia. Some of the recommendations in #1 will cover this. I don't have any recent recommendations to give there, but I'm sure there's lots out there.