Long start post deserves a long answer 
Zigbee
OpenWrt does not have out of the box support for zigbee2mqtt or USB Zigbee dongles. I advise to designate separate devices for Network routing and Domotica
Access Points
Do you have a large multi-floor area that you need to cover with 6+ AP's?
FYI: my house is 135m2 - I placed one EAP615 in my living room at 2m height above surface near backyard garden and another in the stairwell between 1st/2nd floor and this provides perfect wireless coverage on all floors and (small) garden.
These accesspoints are well supported and problem-free since I bought these 21 months ago (together with 86 mm wall junction boxes).
Power consumption is around 4W and PoE passthrough is indeed a nice extra feature. See here for a review
VLAN
For a VLAN setup you need to configure VLAN id's on Router, Managed switch and Access points. You can opt for either a full tagged- versus a mixed tagged VLAN setup - I tested both and eventually decided to choose the mixed tagged VLAN setup. An example of my setup is here
Central Monitoring
If you want you can export collectd output from Access Points + Router to a Grafana Server. An example can be found here
Central Configurator
Possibly this tool is useful to push configuration to several Access points (on the other hand: once you have setup one Access point it is only 5 - 15 minutes work to replicate the config to other Access points)
For a complete list of existing and new hardware I would recommend:
- Modem Fritzbox 7560
- Managed Switch Netgear GS308EPP or GS316EP (suitable for multiple PoE powered Access points and possibly other PoE powered devices like PoE cameras)
- NanoPi R5S as Domotica server for Zigbee2MQTT, MQTT, Home Assistant, Sonoff P stick (and possibly Grafana Server)
- NanoPi R5S as OpenWrt router (NanoPi R4S is highly recommended as well)
- EAP615-WALL as OpenWrt Access points - with good placement 4 might be enough instead of currently 6 (?)
note: to get an idea of OpenWisp capabilities look at https://openwisp.org/demo.html