1. The biggest issue is that Betrifill allows access to its platform using Metamask wallet or getting registered using email.

for me i am uncomfortable to pay fees they charge,
and there are lot of others platforms available to exchange crypto like bitrefill

you can use etsy there are many many many many items listed for selling and you can also sell you stuffs there like digital products or physical
and check this article for more : https://www.gobankingrates.com/money/business/major-companies-that-accept-bitcoin/