Is this phone also more secure?

Probably not.

Apple & Google have spent considerable amounts of time building out hardware security infrastructure for their products that I find it extremely unlikely Fairphone would have been able to match.

For example, the popular alternative Android OS GrapheneOS only supports Google Pixels, because: (Emphasis added by me)

"There are currently no other devices meeting even the most basic security requirements while running an alternate OS. GrapheneOS is very interested in supporting a non-Pixel brand, but the vast majority of Android OEMs do not take security seriously. Samsung takes security almost as seriously as Google, but they deliberately cripple their devices when unlock them to install another OS and don’t allow an alternate OS to use important security features. If Samsung permitted GrapheneOS to support their devices properly, many of their phones would be the closest to meeting our requirements. They’re currently missing the very important hardware memory tagging feature, but only because it’s such a new feature"

If even Samsung, the only other phone brand on the market they consider close to meeting their standards, doesn't support every modern hardware security feature, and deliberately cripples their security for alternate OS's, as a multi billion dollar company, I doubt Fairphone has custom-built hardware security mechanisms for their phones to the degree that Google has.