Yes just drill tap and thread a screw anywhere on the buffer tube. This way the stock cannot collapse all the way and by law you will be good.
Last person I know who looked into this got a very different answer from the lab.
Years ago (around 8 years ago IIRC) my friend bought one of those Arch Angel Nomad stocks for his 10/22 and an aftermarket barrel. The dealer told him he would need to add a muzzle device to the barrel to maintain OAL and keep it NR, so he bought one of those as well. Later we were talking about it and I questioned the advice of the store, and I pointed out how some people were modifying those stocks so they can't fold to keep them NR length. He proceeded to email the RCMP about both the muzzle device and the folding stock.
The RCMP response on the muzzle device was does not count towards OAL, and their response on the folding stock was once a folder, always a folder. If it was DESIGNED to fold, it is always a folding stock regardless of any modifications made to it according to the Lab.
Based on that, I would think a collapsible stock would also always be considered a collapsible stock. (My friend opted to sell the aftermarket barrel and go back to the factory barrel which was long enough to keep the gun NR even with the folding stock)
I do not know of any guns where a collapsing or folding stock was pinned, glued, screwed, or otherwise, and the Lab OK'd it for NR sale. The only gun I can think of that was sold with a pinned stock is the Dlask GSG16s with the short barrel, but those never went through the lab because they were NR to begin with. Meanwhile the lab specifically told Dlask no dice when they tried to limit how far the stock could collapse on CMR-30s to make them NR.
