Hopefully someone can give me some ideas on how to best execute this. If you have a wallet with say >20 UTXOs that were previously mixed using Whirlpool (resulting in equal amounts), how can you best move then to another wallet. In this example, one wallet is single sig, whereas the target is mutlisig.

Sending them one by one is troublesome for two reasons.
a) fees for >20 transactions
b) timing the transactions so it's not obvious that they all moved at once

If they're all consolidated, you've just undone all the mixing previously.

I saw some privacy discussion here https://bitcointalk.org/index.php?topic=5469997.0 so maybe @satscraper has some ideas?

Cheers