I’ve been looking at it.
You want torque sensing (cadence isn’t great), so the most obvious solution is a tsdz2. If you have a standard threaded bb you can make it fit but the chain line may not be great, and on a full sus will probably need to get a bit creative as you can use the rear torque arm (I was going to brace off the front and connect it with a battery mount). Very much doable.
On a press fit it’s still possible, but need adaptors and an axle extension kit or use a 100mm fat bike version with various spacers. Again chain line may be bad. I need to measure up mine and see how my tsdz2 squares up.
The cranks are square taper and 175mm, and the q factor is wide. However, they are cheap and it’s not a huge worry. The BB axle, bearings and sealing is really basic and the tolerances aren’t exactly brilliant, but fortunately it’s also very easy to service.
The battery is probably the easier part. You would need to go custom with a custom bag, but worked out that even on a Jeffsy you can fit ~480W battery in (and building a second battery wouldn’t be overly expensive as you only need to build the bare basics). Would also be a very low centre of mass.