The best answer still is contact the pool operators and ask. Worst they can say is no.
They will probably say no the accurate point is 99% hahaha
But, if there are blocks that are not full (has been a while since that happened), they may be interested in taking your transactions (free extra money). But none of them do by default.
That's the point.
In today mainnet the possibility to get approved by using 0 fee is impossible in my opinion I regulary check mempool.space even when the network is doesn't have congestion they might approved with above of 3 sat or 4 sat.
Normal Range is between ~10 sat.
and the other things fee is making the mining profitable for now they get block reward but when the cap 21 million btc is out transaction need a fee to attract approver/miner