GA4 backfill - data transfer service

[PA_admin]

Hello,

Like many GA4-BigQuery users I've misunderstood the GA4 data "backfilling" capabilities.  This is partially based on documentation that referenced the UA360 enterprise service. 

The only service provider that I've been able to find that specifically offers to set up GA4 historical data backfill is Supermetrics.  (Correction: Supermetrics uses the GA4 API with all the associated limitations.  I was mislead into thinking that Supermetrics was operating differently from windsor.ai or analyticscanvas.com, but they are not.)

Does anyone know of any other options?  Analytics Canvas also has an option but it uses the GA4 API and that, strictly speaking, is not the same thing as a true GA4-BigQuery data backfill.  

Is there no paid Google option? Don't they realize that users would pay $$$$ for this?

Any thoughts are appreciated! (Helpful thoughts preferred.)

Thanks!