Note that you don't need partnerships with exchanges to do this. You just need API documentation.
You're just providing software and possibly running (that is, arranging to run said software on some cloud service) software for people.
Also, you might want to look at hummingbot.io .
One of their models is aggregating market-makers.
Exchanges and some coin promoters pay rebates to large market-makers.
If you use hummingbot to do market-making, they'll include you in their pool (which consists of lots of small market-makers that the exchanges and promoters won't deal with individually) and give you a proportional share of the rebates that the pool earns.
Yes, that aggregation does involve dealing with exchanges, but maybe you can come up with an angle that doesn't. Or, maybe that's an easy relationship to arrange.
