The service OD is providing is liquidity - and the risk they are taking, which they are compensated for, is liquidity risk. This is what 'market making' is - you stand ready to buy & sell and create efficient market.
Beyond the 'data science' of pricing the property, and the tech of automated visits, - the main operational task would be to build an efficient market making business. Anyone who has spent any time in a bank trading desk would know how difficult this is. In a rising market - volumes and upward pricing and demand all tend to go hand in hand - the real test, will be when when the market turns - and maintaining liquidity (and a thin 'bid-ask' spread) in a falling market.
Someoned use the analogy of London trading houses... Another good analogy would be what Marc Rich (and others) did in the 1970s when the broke open the oil market - which had been dominated by long-term contracts - into a more liquid 'spot market'. OD is trying to create a liquid, 'spot market' for a previously illiquid market.
OF course - the market which need the most liquidity (ie the ones outside the 4-5 main metros) is where providing liquidity will also be the hardest. Unlike bonds, shares and oil - housing is not 'fungible' (for one, you can't move a house).
Sounds like a difficult but valuable enterprise - good luck to you and your team.