I would start with the following section of the forum. There’s lots of great stuff there.
In the new architecture, there are three different types of devices:
Hub connected. Zigbee and zwave Devices will either have to use stock DTH is or will have to be written as “edge Drivers.“ The good news is this will all be local in the new architecture.
Direct connected. Samsung uses this term to refer to Wi-Fi devices which don’t have their own cloud. they will be able to connect directly to your smartthings account. Sonoff is a good example.
Cloud connected. Also called cloud to cloud. This is everything else, which is either using a manufacturer-provided cloud or hosted by you and then communicating to smartthings. So everything from Lutron to Devices using eWeLink.
As far as your specific question about your smartapp, you can go ahead and ask in the support section of the developers section of the forum and see what people suggest.
As @jkp Notes, a lot of this is still in development, and not everything is documented yet, but you should get lots of good advice in that part of the forum. 