I understand that one requirement for getting a driver's license is spending 6 hours of supervised driving with an professional instructor. However, with COVID-19, is this requirement still in place because of physical distancing rules?

Many things have changed due to COVID-19, but I think your best bet is to go online to DMV website & ask. Though, I had a question about my car registration & was near Santa Clara Flora Vista DMV, so I walked to back of office where they were doing car inspections & asked the employee...worked for me. Very courteous & helpful.

I don't think that is a requirement in California, rather just a suggestion to do good in a behind the wheels test.