US National Parks: new regulations allow e-bikes up to 750 watts
https://electrek.co/2020/10/03/us-national-parks-services-updates-regs-allow-e-bikes-up-to-750w-with-exceptions/
A quick search on Google turned up this plugin kit:
1.7KW DIY kit for $3,400.
http://www.pluginsupply.com/pricing/
Also:
Products are also available without cells, without a charger, or without a BMS. Email for price.
Maybe some of the battery gurus might chime in.