sell items on poshmark, letgo

Nope, person with H1 cannot have active participation in any other service which generates income.

No, you're forced by law to keep the junk you bought for yourself, indefinitely. You can only sell things under the table, even if it is another table. Lol

I think you can if it’s under a certain amount per year,and in that case you won’t get any tax documents from these online businesses. Please check, I came to know from a friend who is on H1B

Lol