If you want to carry tools and gear, I recommend a 3-wheeler. What the tires can safely carry can be a limiting factor. If you are going with a heavy bike, ensure brakes are capable for the load - possibly discs. If you are going to go with a lithium battery technology, get a good BMS and charger from the same vendor as the battery pack. If you are bargain-hunting, this is a low-margin business and finger-pointing is common if your charger and battery don't come from the same source when you have problems. Try to find vendors who have been around for a while with a good rep, lots of these small operations come and go. (For that matter, some big ones have disappeared or exited the e-bike market, too.) My time from e-bikes was pioneering times and pretty much everything was hand-rolled. (I was part of the campaign to make e-bikes legal in Ontario.) I have some webpages from the time that might be of interest to some. It's old school, but I'm still a fan of lead-acid batteries. Heavy, but can be advantageous over the drive wheel(s). However, they're relatively cheap, will last with a good charger, and there's a core charge to recover at end of life. I still maintain a distributorship for lead-acid battery chargers for a few die-hards. Anyway, if you want to see some old-school stuff on e-bikes:
https://www.econogics.com/ev/evbikes.htm
Also, if you're going to ride on municipal roads or bike lines, especially with a heavy bike, check your local rules on e-bikes before making your purchase decisions.
