Will my existing Zigbee bulbs and Z-Wave switches work with a new hub?

Generally yes for standards-compliant devices, though reviewers note that proprietary ecosystems can be restrictive — r/Not_Enough_Tech and r/Aqara threads flag that some SONOFF and Aqara hubs only fully integrate that vendor's own devices. Multi-vendor hubs like Hubitat, Aeotec/SmartThings, and Home Assistant via the ZWA-2 dongle are the most flexible for mixed device fleets.