When I used to run e85 in my 02 wrx and 13 brz I used this website. https://afdc.energy.gov/fuels/ethanol_locations.html#/find/nearest?fuel=E85 That being said your best bet around the metro for e85 is likely Holiday stations, Kwik Trip, or Speedway.
I've found Minnoco to have the best ethanol content (summer mix around 78%) as compared to Kwik Trip, Holiday and Speedway (around 65% year round).
I still found the website to be alot more up to date then any app that was available. This was 6+ years ago though. On road trips I would throw a 5gal can in the car and fill it when I filled the car so I had extra on board to ensure I could get to E85. With the BRZ it was flex system so I could put pretty much any grade of fuel I wanted in and it would adjust on the fly so I didn't have to worry about this.
I would stick to the website over the app(this is as of 2 years ago), buddy of mine had to convert his 337 GTI back to premium/race fuel because e85 was scarce outside the midwest and getting scarcer.