FWIW I self-published a novel on Amazon/Kindle in (I think) 2013. It was great fun and it sold a few copies. I do know something about design and typography (I used to work in the business years ago) which made the process relatively easy. It is fairly straightforward so I should think anyone with reasonable intelligence could handle it.
Back then you could only publish on Kindle, but I think these days you can self-publish digitally printed books on Amazon which are fairly cheap, but Iβve never tried that.
DM me if you want to talk specifics.