Of all the bike shops in Boston there is only one that I know of that sells wheels for older bikes. There are multiple widths between the dropouts and for the gear cluster for 5, 6, 7, etc. speed hubs. There are multiple rim diameters. There are multiple spoke patterns.
That alone makes it unlikely that, even if you are not alone, there aren't enough of you to matter when the FOB price of a basic e-bike is about $300.
Retrofit markets for anything less permanent than a house are very very tough.
I live in New York and we have tons of bike shops. Actually the area I live in attract a fair number of tinkerers and it's not unusual to see some weird contraption affixed to a vehicle that was formerly a bike. And used bikes in pretty good condition are bought and sold here ( sometimes even bartered ) for $180 - $300.
That alone makes it unlikely that, even if you are not alone, there aren't enough of you to matter when the FOB price of a basic e-bike is about $300.
Retrofit markets for anything less permanent than a house are very very tough.