We use Okta internally where I work and it's been fairly smooth as far as the end user experience. I'm sure it hasn't been perfect but it's always a pleasure having one sign on for everything

My team did use Okta React briefly for an internal project but we couldn't get it to play nicely with Cypress (e2e testing) so we ended up removing it sadly.

I'm pretty sure we had just implemented it incorrectly though since we were still getting to grips with React at the time (as a team that previously had little to no combined UI experience) :)