@LeviKornelsen I recall Paranoia had one in the early box set.
The paperback Elizabethan RPG Maelstrom had one, as a nod from the author to the publisher, that it was a bit like those Fighting Fantasy books they were already printing.
Laserburn, which was essentially a skirmish 15mm wargame, had a solo adventure book called Scavenger.
@LeviKornelsen the Stormbringer Conpanion had a solo-adventure.
ICE produced Middle Earth CYOA books you could play with MERP or their own rules.
The Lone Wolf RPGs used a system derived from the gamebooks.
As a side note: my cousin used the dungeon generation rules in the DMG to play solo AD&D 1e
@LeviKornelsen GURPS also had three solo Conan adventures: Moon of Blood, The Wyrmslayer, Queen of the Black Coast. Paranoia had an unnamed solitaire adventure.
The Blood Sword series wasn't game-mechanically a spinoff of Dragon Warriors but it's set in the same world.
@LeviKornelsen There were actually a number of GURPS Solo adventures for Conan and a couple of other settings. West End Games typically had a solo adventure as an introduction/tutorial in a number of their games, but I don't know if there was an actual product from them.
@LeviKornelsen Call has them, Runquest too. I just presume there was a Traveller one also. I think all of the ”classics” that existed in a certain time range (early 80ish?) atleast made an trial one.
@LeviKornelsen TSR published a line of CYOA style books with D&D branding. Gamma World, too. I don't believe there was ever any game mechanics in them.