I love/loved zip offs but now find the legs look rather baggy for today's fashion when leggings seem to be preferred.
I've 2 pairs North face and 2 pairs of Royal Robbins which have a gusset on the lower leg, which is closed by Velcro, to allow them to be taken off over boots. Bought in 1997 I am wearing the shorts part now, which are a bit shorter than more up to date ones.
I just love the adaptability - no decisions whether it is a shorts or legs day - just change with the weather. Less to pack on a multiday walk.
Seems the Royal Robbins, (with Velcro leg gussets) are still available. Warning - sizing is american
https://www.amazon.co.uk/Royal-Robbins-Womens-Classic-8-Regular/dp/B001MS87PY/ref=asc_df_B001MS87PY/?tag=bingshoppinga-21&linkCode=df0&hvadid={creative}&hvpos={adposition}&hvnetw=o&hvrand={random}&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl={devicemodel}&hvlocint=&hvlocphy=&hvtargid=pla-4583520385790127&psc=1