I'd encourage you to give React a try for this use-case! I've done this exact thing -- slowly introducing React in certain places in a large web app -- and it's

I'd encourage you to give React a try for this use-case! I've done this exact thing -- slowly introducing React in certain places in a large web app -- and it's worked great. You're right that tooling/tutorials are mostly geared towards SPA usage, but React itself is designed to work for both. You'll have to decide on a pattern for "bootstrapping" React in a given page or element, since there aren't well-established best practices, but after that it's smooth sailing.