Is client-side React really that bad for SEO?

I build React-based business/marketing websites - content driven websites where SEO comes into play.

Now, common wisdom dictates that such a website should be static or at least SSR. So you want to use NextJS, Gatsby or another similar framework. But I've been reading about how Crawlers have the ability to execute javascript now so theoretically if your client-side js is fast enough - it should still work for SEO purposes.

Does anyone have experiencing optimising client-side React Apps for SEO? Is this doable or am I deluding myself?