Thanks!
Settings > General > Browsing > Always underline links
(or in about:config set layout.css.always_underline_links true )
It's visually noisy tbh, but I'd recommend to stick with it for a few days and see if you can get used to it. It took me about two days. So nice to see where the "buttons" are.
It also works on Firefox for Android through about:config, which is ostensibly unavailable, but not really: chrome://geckoview/content/config.xhtml - from there, you can also re-enable about:config by toggling general.aboutConfig.enable
Interesting. Chrome doesn't have this option, but if you have stylebot or other extension it's easy to add a global CSS rule that adds it. I'll try it out for a while and see how it goes.