$1 billion BMS Ooops...

A hybrid system with a gas engine wouldn't have the pucker factor associated with starting a
gas powered motorglider to avoid a landing: if the hybrid engine doesn't start, it just means
your potential retrieve distance is shorter, instead of an imminent landing.

I'll wade in here with some experience. Top Flight, a Boston startup specializing in hybrid propulsion systems, spend over half a decade developing their power unit. The hardest part for them was developing a unit which was reliable. Motors don't like vibration and they don't like heat. Combine the two together and the motor is not long for this world. It took a lot more R&D than anyone expected to make a lightweight package which could survive.

I would not expect anyone to be deploying this technology anytime soon. If and when it is commercialized, it will be useful for ferry flights of electric aircraft. For any use which requires permanent installation, you're probably better having it drive the propeller directly.

eGliders, I sense a tone here which is reminiscent of discussions about finally putting the 2-33 to rest. The US is no longer the forefront of light aviation, so we need to look east to see what the trends are. We know that leading glider manufacturers are racing to bring eGliders to market. A gentleman who works on glider competition rules noted this summer that glider records are falling left and right to eGliders. There is a growing group of amateurs who are pulling their engines out of their gas self-launchers and replacing them with electric (If you'd like to be a part of this group, DM me). The future was yesterday, but like any future it doesn't arrive at all places at once.