Best seat cushion for my mesh desk chair for working from home, for my poor bony butt bones, and my legs don't fall asleep?

Drag yourself to the local store that sells chairs etc.

What is comfortable for one person is torture for another. Somethings have to be purchased hands on.

If your legs are falling asleep it probably means your seat is too high. If you lower it, that should give some relief. As far as a cushion goes, I can't help too much. I had one for my last chair and it worked fine, but I ditched the chair for an Aeron and haven't had any problems at all. As far as I know, any cushion is gonna be just fine. Padding is padding.

You can also find steelcase chairs on eBay for reasonable prices. They have all the adjustments and a wide variety of material options.

Tempur is a crazy expensive brand, but does wonders in my case: https://www.amazon.es/Tempur-0855aj-Coj%C3%ADn-Asiento/dp/B001KALM3I Alternatively, the one below has also helped me a lot: https://amzn.eu/d/bUeqLi6 All in all, as someone said earlier, it all varies from one person to another, but there you have my two cents

I’ve had good results with the cushionlab car-specific one. I know they make a regular one, but the car seat shape works great on the particular mesh chair I have for some reason. Getting out for an occasional walk helps a lot too, even 10 minutes.

Same as you. Trust me when I say this is the best chair I've ever used. 5 years on and still a solid chair.
https://www.staples.com/union-scale-flexfit-hyken-ergonomic-mesh-swivel-task-chair-black-un59460/product_990119

Gaming chairs are scams. Overpriced and just have fancy colors on plywood. Get a solid officechair. They make their chairs sturdy and ready to have someone sit in them for 8 hours a day 5 days a week.

Mesh is another huge +1, this chair keeps you much cooler. People think they want leather or something. No, it gets too hot, and if you're sweaty at all it's sticky, and they don't last well. A solid mesh keeps you cool, supported, and your bony ass can sit comfortably for long periods of time. (Just remember to stand up every once in a while, for health)

i think people have the chairs and cushions covered.

instead, i recommend you also look into footrests. someone already mentioned lowering the chair to keep your legs angled properly, but that may make it uncomfortable to work if your desk is at a fixed height.

I've tried a bunch of different seat cushions/modifications and everything I've bought that's explicitly for office chairs has sucked.

I bought a trucker seat cushion from a loves rest stop on a road trip and started using it for my office chair. It's been really nice. Only problem is that it tends to slide a little, but my cheeks are cozy af for my 8 hour work days.

I'll say that some chairs are more comfortable than others, but a standing desk is finally what felt the most comfortable for me.

I'd just get a chair that's comfortable without any add-ons. I have a Steelcase Leap V2 at home, and a Steelcase Amia at work. I can and have sat in these for 16hrs plus in a day. Tempurpedic also has nice, thick butt cushions in their chairs at a fraction of the price.