Ah, I either didn't know about the term threaded code or forgot about it. Thanks for the pointers. (Replying to you but also the sibling comment since both were posted around the same time.)

At first I was thinking of cached interpreters as often seen in video game console emulators, but actually, this reminds me more of the "virtual machines" used in executable packers/obfuscators like VMProtect and Themida.