My advice would be to dip your toes into some of the languages / frameworks that the "specific tech stack" jobs are wanting, so you at least have some exposure to it. Then, you can focus on selling your wealth of general programming experience and transferrable skills to bridge the gap.
A good lens might be to view those positions as senior first, and technology second, even if you don't necessarily voice that perspective in the cover letter / interview.
A good lens might be to view those positions as senior first, and technology second, even if you don't necessarily voice that perspective in the cover letter / interview.