We are hiring Senior Full Stack Engineers. We care about hiring engineers that have experience solving problems across the stack, have a willingness to learn, will bring something to the table and fit into our culture. If we see that you have that, teaching you React is not a big deal. It is more important to us that you know the core languages well and their best practices than framework X.
Feel free to apply to https://boards.greenhouse.io/followupboss/jobs/84965
or reach out to me directly at anthony at followupboss and we can chat further.
While you may be senior level to a recruiter, what we consider senior is usually quite different. Regardless of your situation, you would be competing against other potentially more qualified candidates.