There's a notion of non-outsourceable Proof-of-Work puzzles, and Ergo Platform cryptocurrency which has Autolykos PoW algorithm which prevents pool formation ( see https://docs.ergoplatform.com/ErgoPow.pdf for details).

However, if smart contracts are powerful enough, still miners can do coalitions for most of NO-PoW schemes using collaterals , see this paper of my co-authorship https://eprint.iacr.org/2020/044 (published @ FC'20).

So please consider your scheme against smart-contract powered pools.