It’s a thing that Traveller players do—play with the system solo. Not playing the game or fiddling with the rules. More like running through character creation over and over. Or working through ship design to see how much they can pack in to a 400 ton far trader.
Embracing that style of play, Zozer Games has published Star Trader, a set of rules for solitaire merchant play using the Traveller system. The 28 page ebook includes flowcharts for buying, moving, and selling cargo; rules for trading without a ship; and, of course, a bunch of tables, such as planetary events and ship encounters.