do certain development technology choices make recruiting harder?

Yes. I've been on both sides of the equation. If you are mired in legacy tech and using outdated process, you aren't going to be attractive to many developers. I did a stint with a company that turned into a VC Software holding company. IE they buy good stuff from other people and milk it dry while it rots on the vine. Recruiting and retention were both challenging.

On the other hand if you are flashing all the new hotness, you will get a lot of attention.

I think the best place is somewhere in the middle. Now if you are using the new hotness but in a niche tech you will probably have to try harder to recruit and as others have mentioned show a commitment to developing talent.

Harder how?

Generically, if you choose something super popular, you'll have many options but likely an oversaturation of candidates that say they can do said technology and it can be hard to separate wheat from the chaff. Niche technologies can attract passionate and eager people, but the candidate pool will be smaller and likely less experienced with the tech in production.

Funny that the Python from Python paradox has gone the other way.

Candidates will likely evaluate your company using Maslow's hierarchy of needs (intentional or not). Compensation, the projects, and their manager are the primary factors. An uncommon dev choice shouldn't be a blocker, as long as you set a path to learn it on company time.

required punch card FORTRAN would certainly limit your ability to hire