Getting to Alyx seems like a big problem so I’m not sure if this is possible.
I’ll mess around with this at some point in the future. I’m not sure that you can grab the gravity gun and stay completely in the wall either.
I tested it originally with sv_gravity 0 so I could conveniently savebuffer up and I managed to do it but for some reason with normal gravity I would go in random directions horizontally and wouldn’t get it. Granted I didn’t try it very many times but yeah it might not be possible.
The first part could be possible with SPT. I don’t know how to get back though since the whole last area is seemingly surrounded by clip brushes.