I will agree the devtools are not always as polished, but actually React and Redux debugging tools have worked fine for me. I have these installed:
https://addons.mozilla.org/en-US/firefox/addon/react-devtool...
https://addons.mozilla.org/en-US/firefox/addon/reduxdevtools...
...And I don't really recall many issues.
Ever since WebExtensions, there's not really a good reason for the devtools to be much worse on Firefox.
If you have used these extensions and have issues, I'd love to hear them. I've done React/Redux dev on both and I don't notice things working significantly better in Chrome. (Admittedly, I haven't done any in a few months.)
The only real thing that gets me now is the lack of being able to inspect WebSocket frames. :(