Looked at E-bikes for a while now, thought about kits, hubs etc, some good gear and cheap crap.
The problem is assembly and matching all the gear together, including electronics, batteries and brakes.
Good to get around, quiet, can tow a little trailer too, off road.
My conclusion is to wait and look for a good 'BUY' and just buy the bike assembled to go.
An adult bike can be had for as little as $850.00 delivered at the right time on Ebay from an Australian warehouse.
Most controller software can be reprogrammed for significant speed and performance upgrades, but at the risk of breaking the law
and lower battery time.
Most hubs are rated a lot higher than they are labelled as.
Crank mounted motors are meant to be really good but have been known to break cheap chains (motors can be modified a lot)
Build time is not always as fast or simple as it seems, and your warranty is at risk if the seller believes the problem was your build.
4 months ago I looked at this one -
https://www.ebay.com.au/itm/ROKETTO...045255?hash=item3b3965d447:g:T40AAOSwveNeAIQ5
Good luck.