Can the voucher be returned to points? I would never take the voucher during COVID for cancellations, I would just take the points back. Are you sure you cannot get the voucher refunded to points? Assuming not some random thoughts. To answer your question yes these days domestic flights can be a good use of points. With cash prices these days I am often getting 2-3 cents US of value out of Delta economy bookings via VS points for US domestic use.

The VS surcharges are pretty insane but compared to cash prices maybe less so. Air France/KLM will have lower surcharges if you can find availability via VS. VS surcharges ex-TLV are quite low back to the US (like $250-ish in J). Booking two one ways will lower your surcharges generally speaking if you are US based. VS is also good for short haul flights in Europe on AF/KLM. Neither VS/AF/KLM/Delta in a quick search fly to New Zealand so you'd likely have to use your points to Australia and then get a short haul flight from there.

If you are flexible you should be able to find something. Also I haven't looked at this closely with VS but BA (which has similar surcharges) it can often be cost effective to buy a cash ticket and then upgrade the the class of service using points.