Semiconductors are not fungible; you can't substitute a different chip because the one you need is unavailable Actually in some cases you can. There are nomina

Semiconductors are not fungible; you can't substitute a different chip because the one you need is unavailable Actually in some cases you can. There are nominally package and pin-compatible versions of popular designs from multiple vendors, at least lower end ARM chips from STMicro (which are affected) and older designs like the 8051. That said, they may not be 100% compatible in other aspects, such as clockspeed and electrical properties, and most new devices designed internationally prefer higher-end MCUs.