Solo via programmed adventure modules ( a la T&T, TFT, Lone Wolf, Fghting Fantasy) and solo via rules process (GM emulator, or self-honest use of player-driven rules like Blades in the Dark) are missing from the list, as is "play-like prep" ...
... Play-like prep is common for GDW's lineage, including Traveller, 2300, Dark Conspiracy, En Garde [now owned by Margam-Evans], Twilight 2000; and for some of FGU's, most notably Space Opera. The minigame character generation is not unique to GDW, but ultimately appears to have been their innovation in En Garde, and from that spread to all but two of the GDW released RPGs I've seen. (Those two being Dangerous Journeys and Cadilacs & Dinosaurs.) Traveller also has a trade and commerce function that can be solo played. If you stick to books 1-2-3, you can run a merchant game with random encounters entirely by the tables. Rolling up Traveller maps is also a great solo play-like prep element.
I've done rules prep as a solo activity, working on several pitches for my player group. I am planning to (soon as I can find my copy) replay Hell On Wheels, and rolled a few characters for 4th ed Twilight 2000 KS Backer Alpha Draft... in addition to running two games a week.