I would argue that reset style sheets or normalizers should be part of your "minimal web dev" process, even if you roll your own version. There are so many browser nuances that these things fix so that you don't have to hack it later down the line.
For example, setting the box sizing properly in order to ensure consistent widths regardless of borders or padding.
Few devices (usually the slightly older fw locked devices) which can get a reuse on local net will get some reuse benefit if you added polyfills. I am doing this by conditional "polyfills with SSR" with nginx/lua at the moment. (kindle os/etc. is a pretty good catchall proxy for those browsers; since they still show some html, you can get a very reliable static+interactive (page refresh syncs nicely with the latency) use out of them. (actually, just to periodically update the view of some react page, running headless...)
Edit: Well, that's an extreme, but it has happened that latest react code won't work on a newly unwrapped device still awaiting next fw update).