Mento → https://mento.finance/
For a user, it feels like a swap, but technically, you are minting or burning cUSD/cREAL/cEUR by interacting with the reserve.
Please note there will be soon some major upgrades happening:
Mento Core Contract Upgrade #1 - Multi Collateral Mint
There are some aggregators like matcha already live:
https://www.matcha.xyz/markets/42220/CELO
The mentioned Celotracker and swappa also work as aggregators.
defillama meta-aggregator (somehow only uses matcha routing):
https://swap.defillama.com/?chain=celo&from=0x0000000000000000000000000000000000000000&to=0x765de816845861e75a25fca122bb6898b8b1282a