I own small hosting company, specialized on shared hosting for Bitrix/Bitrix24 cms/crm. Bitrix is known to be badly optimized and are heavily using mysql.
We did tests on real load (on modern server hardware with NVMe) and our results are pretty expected - mysql on zfs works about 3-5% slowly with proper optimization compared to ext4. But zfs has some benefits for our workloads and we are using zfs a lot.
The main things you mostly want to configure is recordsize - it must be 16k for mysql folder. Otherwise you will suffer from write amplification problem.
Also, atime should be always off in all real life scenarios.
If you expect much benefits from compression you do not have to swith to zfs, you can use compression by mysql, it is supported for years (since 5.5 I suppose). Google about “mysql row_format=compressed” for details.
Per-column compression is also possible since mysql 8.0 as far as I remember.