From what I understood, Athom aims at companies creating their own apps, and have them published to Homey cloud for an annual E100,- fee. Also need the apps to be rock solid, while they run on a world-wide shared platform.
When there’s 100 apps with issues for Homey Pro, only these 100 Pro’s can be affected.
The bridge by the way is just a physical add-on for Homey cloud to include local radio’s like zigbee.
If you want to play and test, I’d recommend a (used) Pro (seen it for sale for E75,- already).
As far as I know there isn’t a virtual Homey developing environment available at the moment.
Yeah, developing without a Homey is not the quickest way. Of course you can ask some users to test your versions, but it’ll be a time consuming process.
Chance is low, but you can always give it a go at Homey Pro Community App Requests