I’m planning to buy Homey Pro but am not sure if I need the Bridge too or does the Pro encompass everything I need for a Centralized Hub?
Depends, what You need 
But by my experience - HP makes all, the ordinary user needs and there is no reason to buy additional bridge.
NB! It’s about ordinary user, so there may be situation, when You need additional Bridge, but this chance is hmm 1:100 or 1:1000. So, actually, recommendation: Buy the HP first, and after, then, if You see real reason to buy HB to, then buy it.
PS. If this is Your first automation - You have looot of things to do with HP anyway, no need for HB first.
Additional: a Homey bridge only can come in handy when you need IR/Bluetooth/433MHz in other rooms or locations out of the Pro’s signal range.
In case you want to use it for zigbee or z-wave: almost any mains powered zigbee/z-wave device (lamp/socket/switch/…) will do the same as the bridge as satellite does: act as zigbee/z-wave router.
And, you may still need brand specific hub/bridge because the way a specific brand has designed their things.
