Setup advice and suggestions

Hi I’m looking for a little of advice here.
Currently I’ve started playing/testing OH2, before that I was using Domoticz and a little bit of SmartThings, so now a lot of stuff is quite new to me and it takes some time to get things figured.

I live in UK, my setup is quite simple:
Light bubls, remotes, motion sensors are Philips Hue, got few Zigbee Led drivers and power extensions - this is driven by Hue bridge 2
ST hub handles Aquara double switch connected with Sonoff mini(itead soft) and Aquara temp/humidity sensors
Alexa linked to Hue, St and Ewelink
Network is Unifi and house has good Wi-Fi coverage.

So my test setup of OH2 Stable runs on Raspberry Pi 3B, Aeotec USB stick Gen5 linked with Aeotec Power monitor, Aeotec Multi sensor 6, Sonoff Pow R2(tasmota) and Hue is connected as well.
Reporting is done on influx and Grafana running as container on Synology DS713

I’m trying to reduce no of handlers needed to run current setup.
I was thinking to keep Hue Bridge but drop ST, I’m not sure if I’m better off running reporting on DS713(it’s runnig 24/7 anyways) or I should move reporting to RPI which is running OH2. What implications it would have?
If I would drop ST, what I would need to do, to be able to keep using Aquara switch and Temp sensor and Sonoff mini? Flashing Sonoff is not an issue, but not sure how this can be linked to Alexa and OH.
Also would it be recommended to delink HUE from Alexa and link OH olny?
Would it be wise to run Unifi controller on same box as OH2 currenty they run on separate Pi’s?
Can you recommend any other Temp and Humidity (battery operated) sensors, wall switches/remotes (to replace dumb wall switches and hue dimmers) that are not looking like from previous century?

Any advice is more than welcome.