Two appellate courts have answered this question in the affirmative - at least for teachers.  In both cases the teachers requested ADA accommodations involving working from home and teaching classes remotely. Both teachers noted this had been successfully done during the pandemic. However, in each case the court found in-person attendance to be an essential job function that was not capable of being accommodated.  This answer will vary depending on the type of workplace involved but it does demonstrate that courts are still willing to view in-person attendance as an essential job function in the right circumstances.