He has repeatedly said that he plans to nominate a Black woman, so that should really be a prerequisite for any list of potential suggestions. Ketanji Brown Jackson (who was on the Garland shortlist back in 2016) & Leondra Kruger will probably top the list.
If I was on Biden's staff, these two would be immediate frontrunners. Both highly qualified, and very smart. Haven't heard of any other potential nominees that fit the black + female qualifications set out by Biden. At least, no others that are also young enough to serve for decades.
For anyone wondering Jackson is 50 and Kruger is 44.
Pierre-Louis and Montgomery–Reeves should get federal experience before they're nominated, Biden can't afford to get his first SCOTUS nominee held up.