Setting up my new place. Trying to leverage existing equipment

Hi all,

I recently moved into a new house and discovered that the previous owners left behind quite a bit of smart home equipment. I'm completely new to smart homes, but I've already managed to get most of it working:

• Danfoss gateway: Controls the radiators through a gateway connected to my router via Ethernet. Everything seems to be working properly.
• IKEA Dirigera: Connected a few smart bulbs and smart plugs without any issues.
• Sensibo Sky: Appears to control the AC, although I haven't tested it yet.

At the moment, I can control everything through the manufacturers' apps and Google Home.

Now I'm looking for a smart display/hub (something like a Google Nest Hub or an Amazon Echo Show) that can serve as the main control point for the house. I'd also like to connect it to my existing analog sound system using a Bluetooth receiver.

While researching, I came across a lot of posts about Google Home getting worse over time and the somewhat messy Gemini transition. On the other hand, I've also read mixed opinions about Alexa.

Given my current setup, would you recommend getting a 2nd hand Nest hub or and Amazon device? Which smart display would integrate best with these devices and provide the smoothest overall experience?