(Anecdote: I rejected an offer from a YC startup once because ~60% of the process was them fretting about me not having Ruby on Rails experience. I didn't (and don't) want to work for a CTO that doesn't understand that fundamentals travel between languages.)

As the GP said, any CTO or dev lead worth their salt would hire a dev with good fundamentals in the 'wrong' language over one with poor fundamentals in the right one.

You have to do some legwork to identify who these CTOs and dev leads that care about good fundamentals are. You'll need to engage with the tech community around where you are/want to work and talk to people. It's not a numbers game.