HP OMEN 16-b1016ns - About heat dissipation

Hi, I have a HP Omen 16-b1016ns notebook (I7-12700H, 16GB, 1TB SSD and RTX 3060). A few days ago I opened it to do maintenance, since the thermal paste was a little dry, I solved that easily but I had doubts about the thermal gel (researching in another publication I saw that they call it that) found in the vram and the rest of the components. I didn't touch that thermal gel, I simply placed the thermal paste where it belonged and screwed the heatsink.

My doubts:

• Once opened, does the thermal gel lose effectiveness?
• If it becomes necessary, what size thermal pad should I use as a replacement? (I doubt I can find that gel in my country).
• Does the motherboard have thermal sensors near those components? (To know how much confidence I can have in the software).
• What thermal gel do you recommend?

So far the notebook did not present any problems, even after the Furmark and CPU-Z tests.

I appreciate any contributions and suggestions.