I am where you are, Helene. I don't have knee issues, but I would rather do more moderate cycling in both terrain and distance than to get an e bike, unless I was really incapacitated. Like you, I'd find a replacement activity. When we went to Provence last summer, one of the women on our tour rode an e bike the first day. She was clearly not as strong of a cyclist as most of the others, but she *hated* the thing. She said it was heavy and just felt unwieldy. She went back to the Trek FX and modified the mileage each day of the tour.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport