One that I know is rumored is a 1st party Radar sensor that is supposed to be coming soon, which would be them replacing the Continental radars that exist on older models. There's also battery changes, with the biggest being the LFP batteries on the new SR 3. I wouldn't necessarily categorize that under "swapping out" but testing out a new chemistry that will likely go fleet-wide at some point.
One of the big things they wanted to do was create a lower cost model (3/Y) by trying to reuse as many parts and moulds as possible between the two, so I'd actually be surprised to hear of a lot of part substitution since it goes directly against that logic.
In terms of their MCU, they are at V3, with each being a generational improvement over the last (Tegra to Intel Atom to Ryzen) and not related to the chip shortages. In terms of their AP computers, same thing, they had AP1 which was Mobileye rebranded, AP2, 2.5 and 3 which were each major changes to add computing power.