Just this week the New York Times reported the case of a venezolan banker who received a pardon after hiring a former lawyer of the president. There probably will be litigation if they misreport it so this does not seem hearsay to me.
AI readily provided me a list of 8 other well documented cases of "pay for pardons" and offered detailed research on all of them.
Huh, you were right. I chatted with AI for a while on this as well. Interesting cases, especially the crypto king CZ's pardon. Though unproven by courts, their circumstances and timelines strongly smell like pay-for-pardon, even without proof of agreements.