I was able to get my standard kegel pulleys to fit the Onsra wheels after reaming the holes with a hand reamer from amazon and 6mm reamer bit.The fit is still very tight at 6mm, but it works and it’s much harder to find a 6.2mm reamer bit.
Here’s exactly what I bought:
https://www.amazon.com/gp/product/B077M6XPVL/
Thanks @Menjos !!