ATT; Johnny or (Anyone Else that would have a suggestion)

Hi, I would like a custom E-Bike that can climb this 30 Mile Average 6.5% grade climb. I would want a Mid-Drive with a single speed chain (Gates too costly but preferable). The sprocket would need to be the right size for this long, steady climb. A mountain or Hybrid bike style frame would be best. Is there such a thing as a two speed derailleur? This would make it possible to use my leg power on both this climb and also on a flat road, that I rarely do. FYI, I live at the base of the mountain and have climbed it many times on a mountain bike. Here are the stats of the climb: https://pjammcycling.com/climb/156.Mt-Lemmon

I weigh 150Lbs and 5'9" tall.

I know I would need two batteries that I could swap during the climb. Furthermore, I'm older now but would still like to climb this beautiful mountain. I would still pedal and coast when possible. Any ideas would be appreciated :), thank you!