Sorry for the late reply but I just wanted to affirm that the steps you laid out above are correct and that is the way to go about it. Once you establish connectivity to Azure either over OPDG or S2S VPN, you're presented with a wide-range of serverless platforms that'll help you approach any requirement in different ways.
If you haven't already, I would suggest checking out the BizTalkServer Connector. More dedicated documentation for your scenario can be located here as well: Install and use the Logic App Adapter on BizTalk Server