I tried this just last week, and I've gotta say, out of all the templates and frameworks out there these were the easiest to use and tweak.
Because it really is just HTML with utility classes, you never end up in a situation where you have, say, a "card class" you can't really override without a bunch of `!important`s.
Many of the components in Tailwind UI were already in Bootstrap. There's also a ton of free and commercial themes for Bootstrap (themeforest.net, themes.getbootstrap.com, creativemarket.com, creativetim.com, etc)