My take on the OW interview (and not being paid) has been to consider the timeline/context.
I think M had become increasingly disillusioned by royal life not meeting her expectations.
Can’t keep freebie gifts, got a cottage not a palace, criticism for the celebrity baby shower, tours and engagements that she couldn’t pick and choose that were far less glamorous than she envisioned, realising that H was nowhere near as wealthy as she thought etc etc
The solution: half in, half out. Keep the perks, ditch the dross and H was more than happy to keep her happy.
Problem was the narrative that “we want to monetise our titles” was not a good look and they got public push back on that following their statement.
To be able to monetise their position they knew they had to present a “good” reason for why they left rather than money.
OW gave them the opportunity to do that. On a global scale. No, they weren’t paid (unless it was the source of a significant donation to Archwell) , but it was one hell of an investment on their part in setting up a “fan base” that bought their “truth” hook, line and sinker, that they dined out on for quite some time.