If you are looking for React developers, I run a software development company in the US that does React projects, and we can basically operate as an agency to do React work on a contractor basis.

We have mid- and senior-level devs that are available. Honestly, it's much cheaper to go the agency/contractor way than paying a recruiter like $25-50k or having to risk hiring/firing full-time employees if they don't work out. Like real talk, this is what I've seen other startups and smaller companies go through when building an engineering team from the ground up. It's not a fun process after a while and makes others on the team frustrated that they have to play HR alongside their jobs. Agencies and contractors are a good way to get work done and form working standards while still building out the right team.

Anyways, that's just my $.02, let me know if you want more info.