For example my corpo hit manufacturing issues (production capacity) with flash memory, with clock oscillators, with auxiliary fpga. But main chips production was fine all the time during chip crisis as far as I know. So yeah, small critical components totally can be a blocker. Some specific voltage controller is unavailable and suddenly your whole design is paralyzed.

pcbs are also full of a bunch of other components, many of which are hard to get ahold of right now.

I think that's it. PCB itself is rather trivial, it's the RAM, but also things like switching regulators (there are others, but then it's a redesign), maybe even stuff like connectors (which don't burn....).

For a science project, we need to manufacture magnets. It's not easy to find a company who has the right iron right now, and it's hard to get, with long lead times. The supply crisis is real.