We're currently working on a solution to capture data into SharePoint for a customer. One requirement is to capture signatures and I found a third-party provider "Cognito Forms" (www.cognitoforms.com) which supports this and also provides integration with Power Automate so we can easily process submissions.
I've managed to get everything working pretty well but I'm having a bit of trouble integrating the forms themselves into SharePoint. I've created a new SPFX project and have create a webpart but I'm having some trouble with the integration. Their are two methods for embedding are: