I thought the via accelerator was gone!!
As far as I know, Only their exchange closed. The Mining pool as well as their acceleration service remained untouched.
How does that antpool one work? You have to have a bitmain login?
Yes an account is needed but you can register for free anyways.
There's no prerequisites that is stated on their site for eligibility of a transaction. But from my experience, Entered transaction with a higher included fee still gets high priority.
To add on, I quequed lots of transaction with a 1 sat/byte a few days a go but none of them gets confirmed, In the past even a no miner fee gets confirmed within 24 hours.