I've never used a Lisp machine, but based on your description, it sounds like the experience of using them might have been somewhat like using the Oberon system created by Niklaus Wirth- or the other way around (based on a BYTE magazine article [1] about Oberon that I read, IIRC - never used Oberon either).
[1] I thought so because this part of your comment:
>the way each piece of software in the system was practically an API for my own use
matched somewhat with something I read in that BYTE article, which was something to the effect that once you had written a subroutine in Oberon, it could be called from anywhere in the OS. IOW, in a sense, the whole OS was like a single program, that you could program. Cool concept.
Though the Oberon system might have been much less evolved, or whatever - as I said, used neither, just interested in the thing.
P.S. From the Wikipedia article about Wirth:
https://en.wikipedia.org/wiki/Niklaus_Wirth#Humor
[ Wirth has reportedly told the joke that, because Europeans pronounce his name properly, while Americans pronounce it as "nickel's worth", he is called by name in Europe and called by value in America. ]