I did a quick research and I found multiple articles dating back to 2023 talking about a partnership between maverick.game and pinnacle solution. So, I think pinnacle is their odds provider.
But as I couldn't find any official source for this information, it would be better to reach out their customer support or pm their pr (as yahoo suggested) for confirmation.
I think you are right that their odds provider is pinnacle solution. I did some quick comparison of the odds they have on maverickgames.com and on pinnacle.com and they are the same. but anyway, I agree that it would be for the best to reach out to their customer support to confirm it.