I don't know how you would do it on the Monero blockchain, you're the genius with the idea
But, on bitcoin, L2 is how they would accomplish smartcontracts, so maybe you can create an L2 on the Monero chain
Dai is algorithmic stablecoin backed by a basket of crypto assets including Eth and stablecoins created by the MakerDAO
If your interest is algorithmic, you should check out, UST on Terra Luna chain, MIM, Mai, and maybe go full on stablecoin pegged to something else that's not fiat like another cyrpto btc/ftm/avax, heck you should check out Tomb and Tomb forks with their stablecoins peg to a native crypto
There's also rebase coins like AMPL
But all those algorithmic stablecoins are on transparent blockchain, so you can fork and create on your Monero L2 chain?
Go for it, Mr genius Ideaman, you're the best!!