A subject depressingly familiar; the mental burden of which hopefully eased slightly by helping you avoid making the same mistake!
I've damaged my cherished, not-cheap, otherwise cossetted walking boots by exclusively using wax (Grainger's G-wax, FWIW). While perhaps waterproofing, this pretty hard wax / polish barely-if-at-all penetrated, allowing the leather to dry out, harden and eventually crack in areas of high flex
Since recognising this problem I've treated the boots with the Nikwax treatment (forget exactly what it's called) and Kiwi dubbin - both of which have made the leather very noticeably softer and more pliable. This has also made the boots significantly more comfortable..
From this experience I'd suggest that the use of conditioners (which are typically thin, mobile liquids or pastes that soak into the boot pretty quickly) should absolutely be prioritised over purely waterproofing waxes and polishes.
I did go down the conditioning rabbit hole with respect to a leather coat I have; the upshot seemingly being that all treatments degrade the leather to a small extent, however better to have a slowly degrading, decades-old item that's still supple and useable, versus something that's hard, brittle and cracked after a few years.
Mink oil seems to be near-universally considered to be the "best" leather treatment, however carries ethical baggage so personally I'd continue to go with either of the products mentioned above.