>How much work can they hope to do?
A lot more than you think!
Unfortunately, their real problem is getting decent downtime/respite. Under pre-CoViD circumstances, the baby would have been able to spend time at nursery, grandparents, neighbours, nanny etc. Also it was easier for either parent to leave the house for a while. Giving both parents (but more specifically the mother) time to relax, catch up on sleep etc.