For the reasons you describe, I am pretty sure but can not proof it scientifically that:
A 6 wide RAIDZ2 from a single HDD batch offers a greater risk than a pool of 3 vdevs, each with a 2 way mirror, where each mirror consists of two different drives.
I theory you might think that RAIDZ2 is safer here, because you can loose any two drives. In reality I would argue that especially in a homelab or even a business that does not swap HDD before they fail, after 5y of running these drives, the bathtub curve kicks in and mirror is safer.
We recently had this discussion here: RAID Reliability Calculators blindspot - #12 by Sara