I commented elsewhere about endeavourOS, but I have some other wisdom to pass along.
Keep good backups of your personal files, stuff you don’t want to lose, and don’t be afraid to try something new. You dont like something about how your system is running? Nuke it and install something else. Installing Linux is a cakewalk in most distros and rarely takes longer than half an hour (your mileage may vary with the low specs on the laptop)
I’ve learned a ton about Linux by trying many different distros, breaking things, fixing things, and occasionally distro hopping to see how I like a different offering.
There’s a lot of great content on YouTube that can help you learn, and reviews of various distros so you can get an idea of how things work without having to install it yourself. Have fun and don’t be afraid to fiddle with things.
I really agree with you about immutables. Not only are they awkward to use as far as managing and installing software, I feel like they prevent people from learning how a traditional Linux system works by keeping them in the padded cell of read only root.
As far as arch, it only really took me a year of fiddling and learning on Fedora and mint before I managed to get arch running. Yes there were hurdles and growing pain, but it made me a better user.