I bought a spare H4 to try and open, but heating didn't work as it seems to on other headlights. I tried cutting with a jigsaw, but there's a flange on the glass meaning that you can't get up close to the glass to cut, and take out about 4mm of the plastic housing, then of course, you hit the inside reflectors with the jigsaw rendering the thing useless anyway.
I did wonder about using a diamond disc in a grinder or a multi tool, but had lost interest by this point...
OP, great work on the H7s, I would be interested on how you got the H4s open.