Which is weird, because by my rudimentary calculations, all the numbers say it isn't possible; the derailleur movement should be too short.
There isn't really anything to be gained though; although the official maximum sprocket capacities are listed as 34T for the newest-generation road 11-sp. and 36T for MTB 10-sp (except M6000 Deore, which is officially 42T), both have the tolerance to be pushed beyond that. 40T is realistically the most a MTB 10-sp. (except M6000) will handle, 42T gets very rough without a Goatlink. I've heard of R7000/8000/RX800 also being pushed acceptably to 40T, but haven't played around that far myself yet to see how nicely it plays. If a 2x is still desired, I wouldn't push a road derailleur beyond 36T big sprocket, because you need to allow for the front ring difference.
Back to the OP's original question..... SRAM may or may not have got over the design flaw that resulted in shift paddles falling off.... Shimano levers at least stay attached. SRAM's road hydro levers are bloody uncomfortable when you're up on the hoods; the reservoir bodies have really squared-off edges that dig viciously into the crook of your thumb. It's a real let-down because their mechanical brake versions are probably the most comfortable of the lot. 1x might look tidier, but SRAM pushed it because they could never get their front shifting to work..... 2x will give you as much, if not more total range, and with a moderate-sized cassette, better progression through the mid-range gears.
Brakes: There is no such thing as an adaptor that allows flat-mount calipers calipers to post-mount or IS-mount frames/forks. As per an earlier post, there are adaptors to allow post-mount calipers to fit to flat-mount frames/forks, but probably not to fit IS-mount calipers, because I don't think anyone even makes them anymore....... ALL Shimano hydro levers and calipers are interchangeable; although most road systems now come with flat-mount calipers, the first-generation R785 post-mount were nothing more than reprinted M785/M675 XT/SLX calipers. The RS785 revision moved the hose connection and bleed port for more foot clearance, but kept the same internals, and were cross-matched with the RS805/505/405 calipers on all road hydro levers.
On the other hand, SRAM did (or at least claim to) alter the master:slave cylinder ratios between their MTB and road hydro brakes in order to improve the modulation on the road models. You could probably switch over to Level calipers, but I don't know what effect, if any, that would have on brake performance.