Upvote this idea https://community.esri.com/ideas/13853-arcgis-data-connection-for-power-bi. In that idea is a user comment that suggests a workaround. If your form is simple enough (no repeats or attachments) and if you are good at JSON transformation using DAX and PQE, it should be easy enough.
As to using the feature layer of the Survey123, you got to pay attention to your form's schema. Working for my previous employer, I created a complex S123 form that fed the data daily into a PBI report. Between S123 and PBI, I used an ETL tool (FME Desktop) that stored the form data into SQL Server. If you have access to ArcGIS Pro you can use its DataInterop extension to do the same. You have options.
