Some people sell via Instagram things but I have no idea how that works. I know this because someone in youtube video said she sells via Instagram and to contact here there, she sells crafts supplies.
Etsy has a Etsy forum where sellers ask and give advice to other sellers.Buyers and readers also can post questions there.
I do not know exact story but Etsy changed some rules about shipping and international sellers found it not doable for them and left Etsy.
Country in EU I live in. Taxes started control of who sells how much on Etsy. Hobby earnings is a small limited amount allowed and then you have to pay taxes like a business. And the 22 euro rule applies. Buy over it you have to pay VAT customs etc.