I haven’t got experience with SHS myself, but yes, you would be able to transfer your flows. Indeed you would first need to add your devices to SHS. As they will then get a different device ID, you would also need to fix the transferred flow (as they refer to the old device IDs).
You can use this script to achieve that. Before you delete devices from your old Homey, make sure to write down the current device IDs. As you need them as input for that script.
Also make sure your SHS instance has all the apps installed required by the flows. And make sure to recreate the same variables. You might need to update the variables in the transferred flows as well, as they also use a unique ID under the hood.
So it is not a plug-and-play method, but saves you the effort from building the flows from scratch. My tip is to try this mehod first with one flow, to check that the transfer actually works.
