Yes, I have experience working on ebikes, including conversions and stock systems (Trek, Torker, Kona). You are right, the technology is still in the "sorting it out" phase. Kind of like early index shifting where each of the major brands had different cable and housing diameters, nothing was cross compatible. With some creativity and research, some things can be modded and cross compatible.
As I mentioned before, "with some caveats to safety and capacity." I believe that your shop should do what it does best to add value. If working on the electrical components is not within your capacity to add value or poses safety risks (like a moped), don't do it. However, almost everything else on the ebike is common and complies to bicycle industry standards (unlike a moped). So go ahead and replace brake pads tires, grips; get them a comfortable saddle and a good kickstand; whatever.
Maybe your shop operates a little different than most community shops that I am familiar with. The ones I know, for the most part, do not fix bikes. They help people fix their own bikes. Our community shop recently held a frame building class, because it was in our capacity. Stay within your capacity. Most of the negative response to ebikes seems to come from folks who feel it is outside of their capacity/feel like they are responsible for everything coming through the door. Your problems are not their problems, they are your opportunities, which you can choose to take, or not. "That cracked carbon frame, well, I suppose you could fix it, just not here. Call Craig Calfee"
The market will shake out with ebike components, but it will take a few years. If you decide to work on the e-components, you will need a multimeter.