Once you know the exact travel in mm for a replacement fork, it would make your job easier.I don't see any other RockShox options for a 15mm thru axle e-bike?:
There are quite a few:
Here is one with 80mm travel, 110mm boost thru-axle. They also make the 100mm version.
Who says entry-level bikes can’t get all the latest features and performance?. 2018 Rockshox Rudy Gold 27.5" 80mm Solo Air Fork. Model year: 2019. Travel: 80mm. Spring: Solo Air. Hub Spacing: 110mm (Boost).
If you want the very best, you could certainly look at the FOX series. If you can accept a previous year model, you would be able to find an excellent fork at an excellent price like this:
Find many great new & used options and get the best deals for Fox Float 34 Performance Fork 27.5" 130mm 3 Pos-Adj FIT-GRIP 15x100mm Black New at the best online prices at eBay! Free shipping for many products!
Another one. FOX Factory 32 with kashima coating but can only accept tires upto 2.3"
Find many great new & used options and get the best deals for 2018 Fox Factory Float 32 27.5" MTB Fork 100mm 15x110 Remote Ready Boost SC at the best online prices at eBay! Free shipping for many products!