Modern chips made via EUV lithography can be thought of as 3d printed. Like the most mind bogglingly complicated 3d printing imaginable.
I dont think TSMC make ROM chips using their 5nm process but I think they _could_, if needed. So that would be a very compact way of storing info.
Nope. If you stretch the definition of 3d printed that much, then anything is 3d printed.
There is a lot of etching and masking going on in lithography, it is not localised additive manufacturing, the distinctive feature of 3d printed.