If you look at 3:14 in the For Science! deep dive video, in the OSL-25 "Starlab" orbital survey experiment, at the bottom of the experiment information, you will see the text "Crew Required: 2". So I am fairly certain that we do have crew requirements.
And I think this does not mean that experiments may have crew requirements, but rather that the old KSP1 distinction between pilot/engineer/scientist is an unnecessary complication, and they have thus decided to remove that distinction. In this context, that likely means that while you do need a certain amount of kerbals in order to run an experiment, it does not matter who the kerbals are - Jeb is now just as qualified to run an experiment as Bob is.
And honestly, I think that is a lot more realistic, actually! Human astronauts nowadays are trained in basically everything; Everyone needs to be able to fly a ship, or be trained in medical administration, in case of emergencies. Everyone needs to have a solid understanding of engineering in order to troubleshoot and fix issues with equipment. And someone who can only fly the ship, regardless of how skilled they are, are no more than dead weight with regards to the typical mission goals - to do science! And thus everyone needs to be a proficient scientist as well.
Tldr; I believe it is very certain that we do have crew requirements for certain experiments, but that it does not matter what kerbals we bring to do these experiments, as every kerbal should be trained and qualified for any situation, whether that be flying the ship, doing construction/repair work, or conducting scientific experiments.