the relay approach may raise potential safety issues, so it’s just something to think about as you look at those possibilities .
Most stair glides and chairlifts have multiple safety features built in. One is some kind of bump detection so that if the chair runs into something it will stop right away. This protects both the chair and whatever has been bumped into.
Another is an end of line detection, so that the chair motor doesn’t keep trying to push forward past the end of the rail. This can be particularly important if the chair was stopped halfway and then started again. And another has to do with what happens when power is restored after a power outage.
If you use something which triggers the signal from the existing remote, it’s likely that all of the existing safety features will remain active. Because it’s really no different then the button push.
If you remove the existing remote from the equation, and hotwire the glide motor Directly to some automated controller, you run the risk of bypassing several of the different safety features. So you just need to be aware of that.