The box says three players is the minimum, but my wife & I have always enjoyed it 2-player, as well. I used to try modifying the rules (scoring) a little bit, but now I just play it as-written. With only two, it is typical that both players will have holdings in all 10 commodities. In fact, that's an important strategy, since allowing your opponent a monopoly in a commodity gives them 4 points, while laying down a single of your own will cut their points to 3, while giving you 1. That's a valuable 2-point play.
(Conversely, it can be very powerful to play single cards in many different commodities as early as you can, because some of them may score as 4-point monopolies or ties for first place during the early scoring rounds.)
Hi, Mark. The girlfriend and I learned this one as 2-player, but we never went beyond this learning game. We'll try it again and see if indeed it does all right for two.
Have you considered Freight Train for two? The games are related and so share some similarities. Freight Train works very well with two; in fact, given the space this game demands, 2-player is probably the easiest way to get it to a standard table.
2-player Freight Train using the cards from Gloria Picktoria is entirely possible. It requires 9 each of 11 different suits and one card to serve as end-of-round ("sunset") card. The money/$ cards can serve as the additional 11th, and a single wild card can stand in for the end-of-round card.
If you're interested and need a breakdown of the rules, let me know.