I agree, 90km is ambitious.

The Amego lists "The 624 Wh lithium battery provides upto 105 KM per charge on level 1 assistance." I.E. low power. But, perhaps that is what you need.

Some of the batteries are easily removable. I think the Bosch can be easily removed, and you could swap in a spare (which, of course, isn't cheap).

You've got a few choices. > $2000 or $3000, all new tech.

< $1000. Old tech. Perhaps needing some work. Needing new battery. Are the parts available? Modern Lithium battery? How much tinkering do you wish to do?

When you add the battery, prices will go up quickly.