Outside of the limited medical program, the purchase and sale of cannabis are not legal here on an adult-use basis. Although it is legal to possess or gift cannabis, there is no actual adult-use industry.
There are plenty of stores that will "gift" you cannabis if you make a qualifying purchase, but these stores are far from acquirable or financeable. The program is as assbackwards as they come, but if you find the right store, you can pay $10 for a sticker and walk out with a dime bag.
There is no notable activity at this time.
The US Congress governs Washington DC, which speaks for itself. Look for change at the federal level before there is real market opportunity in the District.