Maybe a coil spring, in the shift cable routing, will be strong enough to hold it in low gear,
but give enough if there is a mismatch..

the safety limiter in the front V brake noodle on the consumer
Hybrid bikes like Trek Navigators, is somewhat along that line..

you pull the cable, the housing compresses a spring first, to slow down
and towards the end of the lever travel it pulls like it would if not for the spring being there.

Helps to keep from sending a casual rider over the bars ..