I haven’t looked at that project specifically, but I believe that it would be possible to have a burn mechanism that could work even if the token was in somebody’s wallet, but it would require using a custom smart contract I believe, and I don’t think that the de-facto standard for NFTs on Solana ( aka. Metaplex ) has that feature.
That makes it sound like they might being their own custom NFT contract.
It could be, but you would have to ask the project or find in their documentation what contract they are using. ( and maybe take additional measures to verify the code of the smart contract if you don’t trust them )
It could be a scam. Again, I haven’t looked at the project myself, but be very wary of projects that you don’t know about through trusted sources.
I’m not 100% sure. I think it might require having a web-service that periodically triggers the burning of the NFTs, but how those wallets are chosen is a big question to answer. Also, that might indicate a partial centralization of their solution, depending on how they’ve implemented it.
Anyway, I can’t give you any super-solid insight as I don’t have time to investigate the project specifically, but hopefully those notes help somewhat!