>
comes armchair experts and the potential for insufferabilityHey, I resemble that remark! I'd be maybe a little less armchair with more surplus equipment access, but maybe no less insufferable.
By all accounts, though, a degree of insufferability is no bar to doing worthwhile work; Socrates, Galileo, Newton, Babbage, and Heaviside were all apparently quite insufferable, perhaps as much so as that homeless guy who yells at you about adrenochrome when you walk by his park encampment. (Don't fall into the trap of thinking it's an advantage, though.) Getting sidetracked by trivialities and delusions is a greater risk. Most people spend their whole lives on it.
As for how little any person can know, you can certainly know more than anyone who lived a century ago: more than Einstein, more than Edison, more than Noether, more than Tesla, more than Gauss. Any one of the hobbies you named will put you in contact with information they never had, and you can draw on a century or more of academic literature they didn't have, thanks to Libgen and Sci-Hub (and thus Bitcoin).
And it's easy to know more than an average doctorate holder; all you have to do is study, but not forget everything you study the way university students do, and not fall into traps like ancient aliens and the like. I mean, you can still do good work if you believe in ancient aliens (Newton and Tesla certainly believed dumber things) but probably not good archeological work.
Don't be discouraged by prejudice against autodidacts. Lagrange, Heaviside, and du Châtelet were autodidacts, and Ptolemy seems to have been as well. And they didn't even have Wikipedia or Debian! Nobody gets a Nobel for passing a lot of exams.