I regularly commute 15 miles on my e-bike (just under 1 hour) with lycra boxer briefs (no padding) and regular basketball/athletic shorts. Or in a pinch I'll just use regular boxers under the athletic shorts. I have also done 15-20 mile rides on the e-bike with cargo shorts. The lycra boxer briefs are preferred, though, to help prevent chafing.

Most of it comes down to type of saddle and posture on the bike. On my road bike with a narrow saddle, I prefer bike shorts/bibs (including for commutes). On my e-bike with bolt upright posture and wider saddle, regular shorts/pants are fine, but athletic-style stuff is preferred (no jeans, yuck). My offroad gravel bike is sort of in between and I've done rides on it both with bike shorts and regular shorts.