My understanding is there are roughly 2 types of sanctions:
(1) Blocking US people / companies selling to a sanctioned company
(2) Blocking the sanctioned company from operating in the US
In scenario #1, that would likely impact Ambarella, Nvidia, Intel, etc. but the inventory would be fine.
In scenario #2, the inventory would be dead (i.e., Hikvision cannot sell it). But even for scenario #2, if an integrator had Hikvison inventory, I don't think (though I don't know) it would ban the integrator from re-selling that inventory to an end user.