Passport is different, living person, living witness and lots of attempted malfeasance.
If the will is contentious, eg close relative cut out, it may be challenged by that relative and witnesses mater but having done 4 simple parent/parent in law probates in 10 years I've never had a question about witnesses. Many witnesses pre-decease the will maker anyway, or move away, how could that be checked except for simple public records, yes there was a J Smith living at 2 Smith Street at that time so on balance OK. Civil law runs on the balance of probabilities not beyond reasonable doubt.
I would find a 2 adults, neighbours maybe, living in the same household so who can be together. A couple can both be witnesses. Walk or if you have to drive. Go stand outside their window, sign it in view, leave it in envelope on doorstep, retreat. Get it back In a day or two. I think covid only lives for a few hours on fabric, paper etc not the 72 some have found on hard surfaces. You can check it out to keep everyone safe.