My biggest advice for anyone is to not ignore the traditional advice. Secular meditation practises based on Buddhist meditation take the practise out of its context in a quick and forceful way. Buddhism has had 2500 years to slowly develop and work out what works and what does not. It is quite dangerous to take it and call the parts that do not immediately appeal to the secular western mind, like devotion, worship, c…
I'm going to call bs on your claim that you "personally know two people who went into severe psychosis and depression". Since we're in "my personal experience"-land, I've been meditating and have been around people who meditate daily for 26 years. Never seen or heard about anything close to what you describe.
I actually think that some of the benefits of meditation are adjacent to psychosis, in a way: as you get closer to the "insight" that is the intended result of Buddhist meditation, you are also flirting with losing your grip on reality.
In my case, it went fine. I resolved the experience and integrated it. But I could see how it might go the other way for some.
Professor Britton at Brown has made a career of studying these kinds of experiences, plenty of examples here:
https://www.brown.edu/research/labs/britton/research/varieti...