The main reason nobody's talking about them is that AFAIK nobody uses them either. Most shitcoiners gravitated to their own solutions for muh tokens.
Personally I also don't really care about shitcoi...
So yes, nobody is using them. But they are issued on chain. Asset data is committed into a Merkle tree. The root of that tree is embedded in a Taproot output using a tweak to the Taproot public key. So on-chain, it just looks like a normal Bitcoin transaction, which you are storing.
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