Do i need an IoT VLAN

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The deal is as follows, i have configured 2 VLAN's in my network. The main LAN (VLAN 1) and a Public LAN (VLAN 10), both with their own DHCP server and subnet. The Public is mainly for guests that want wifi access in the house and is completely isolated from my main LAN. Until now, i really didn't bother much with the gaming consoles and the thermostat being on the main LAN but now i got a wifi speaker (from the illusterous brand Xiaomi) as a christmas gift from my work which i have connected once the main LAN to test it and it works really well. The thing though is that unfortunately, i have little trust in Chinese brands and certainly wouldn't want them having access to my main LAN network which has my Nextcloud server and fileserver which contain my personal and company files so after the trial, i disconnected the speaker and boxed it again.

This got me thinking that maybe it is time to have a separate IoT VLAN to connect things that i do not want to have any access to any other LAN resources other than the internet, similar to the Public Wifi. The thing though is that i do not know if you would need to be on the same LAN in orde to play music from the mobile to the speaker or if that all goes through the internet. In the end, the main question is, do i really need yet another VLAN for IoT or should i just use the Public for both purposes. Reconfiguring the existing stuff such as the game consoles and the thermostat to connect to the Public LAN is obviously a very simple operation. Is there anything i am missing here?

Go for it!
I have a Xiaomi vacuum cleaner a this contacts countless numbers of chinese servers...
Unfortunately on my Asus XT9 Mesh cannot create an IoT network, to isolate this guy from my home network. I tried to put it into guest network, as single device, but then cannot control it with iPhone...