On meditation, also partially replying to this: I think it only works with extremely good posture.

I went to various Buddhist gompas where people just sat down on various sized pillows, teachers told people to have straight backs which is something everybody interprets differently (usually, most people tend to make arched back backs, as it feels like the opposite of slouching) and frankly, not a lot happened.

The place that worked best was a fairly strict mokusho Zen center, where all pillows were stuffed to be high and hard, and it was explained to not just sit on them but actually sit on the ground and use only the edge of the pillow to push our lower hip / pelvis forward, effectively making a posterior pelvic tilt or at least fixing our usual anterior one, shoulders back but not raised (during the session the master pushed my shoulders down several times), mind focused on breathing out while breathing in was automatic, and another neat trick was that instead of using closed eyes, they made us keep the eyes half open looking 45 degree down, which is something actually you can see on old Buddha statues, however, usually it just means looking at things on the ground which is not meditation, and they fixed it by making us sit facing a white wall. That worked, that made me feel "spaced out" fairly fast.

But this was the only one that worked.