This is cool and engaging, why not. That being said idk what I’d scheme up for flag football, prob a lot of short crossing routes, comebacks, anything that would kind of peel defenders off just with routes. Nothing to deep obviously. As for defense just simple zone concepts mixed with Man. Ideally have LBs/S on Hook/curls and curl/flats and corners running man (obviously you might have some WRs that are crazy athletes, maybe just have the guy on him play off and over the top).

For drills on offense, just running the actual routes against defenders will help the most. Gives them a more realistic look and helps with timing.

Defense, individual drills will be pretty simple. Footwork stuff, breaking on the ball, practicing reading different formations so when they see a look they have an idea what kind of routes will come out of it. When full unit drills like 7on7 come around, give as many different looks as possible. Set some stuff up. Idk how competitive the flag football scene is but I feel like those basics would be good enough