Is it possible to wear Specialized BG footbeds in regular walking shoes?
I have been told by a friend that I should not.

Is this true??

I wear custom orthotics in normal shoes and specialized blue footbeds in my cycling shoes as a substitute, which the podiatrist approved of, so it’s just the reverse really

Given the Specialized insoles are designed for cycling shoes which, by design, are not walking shoes, you’ll be using something for a job it wasn’t designed for.
Just buy some proper walking insoles.

I wear some in my normal trainers, seem fine to me

try the superfeet insoles – both of my walking boots have them and they are now my comfiest footwear.

I got some orthoheel (I think) from boots, about £23/pair, and wear them in my flat pedal shoes, another pair in my walking boots. Slightly more extream than the BG ones with much bigger arches and more pronounced tilt, so make sure they’re comfortable for you.

Walking in them for me rolls my ankle too far outwards so it feels as though I could easily twist an ankle while walking.

I put some in my running shoes, after speaking to a running shop who said that one of the folk who worked with Andy Pruit has branched out and done an identical product for running. Even the same colours.

Made my running shoes much more comfortable.

Got BG footbeds in my summer and winter cycling shoes and orthaheel sports footbeds in a pair of running shoes. If anything, the orthaheels are more extreme, very supportive under arch with no give. They do help on a long run when compared to comfort insoles.

Why not stick your BG footbeds in your walking shoes, carry the normal insoles and go for a long walk? Any probs, you can swap them back.