Personally I hope Elon steers clear of the government's desire to go electric. Around 400k of the governments 645k are specialized vehicles (military and mail trucks). Tesla doesn't need the distraction. Perhaps some portion of the remaining 250k vehicles can be converted to Model Y or Model 3 but anything that requires Tesla to spend time and effort on custom projects doesn't help the bigger picture.
Perhaps Tesla can work with the government on solar initiatives or other green projects but I hope they stay away from government fleet.
OT shout out/ poke to Tesla:
I would not want Tesla to have to deal directly with the USPS, but I think that they would be an awesome Tier 1 for a company that could build and support the NGDV.
Full electric ecosystem
Telemetry system
Heat pump for winter efficiency
2 and 4 wheel drive variants
Low floors for easy cargo access
Passive entry/ start system
Auto parking brake
Charging tech
Solar and storage deploy at all post offices
FSD/ autopilot for safety and park and loop routes (smart summon dog mode)
Basically, everything but body/ chassis/ interior.
The fleet uses a high amount of fuel per year, so the 165k or so vehicles would give a higher than average emmissions reduction impact.
I was involved with the NGDV RFQ, and I've often thought about about buying an LLV and merging it with an X or Y to show off the concept; but without Tesla support, it could easily result in a sea of warning lights and broken functions.