Like many other security mechanisms VLANs aren't really about enabling anything that can't be done without them.
Instead it's almost exclusively about FORBIDDING some kinds of interactions that are otherwise allowed by default.
So if your question is "do I need VLAN to enable any features", then the answer is no, you don't (almost certainly, I'm sure there are some weird corner cases and exceptions).
What VLANs can help you do is stop your PoE camera from talking to your KNX and your Chromecast from talking to your Switch. But why would you want that? They don't normally talk to each other anyway. Right. That "normally" is exactly the case: one major benefit of having VLANs is not just stopping "normal" phone-homes but to contain any security incidents to as small a scope as possible. Imagine if someone figured out a way to hack your switch (maybe even remotely while you're out!). That would be bad. What would be worse is if that attacker then suddenly has access to your pihole (which is password protected and the password never flies around your home network unencrypted, right?!) or your PC or your phone ...
So having separate VLANs where each one contains only devices that need to talk to each other can severely restrict the actual impact of a security issue with any of your devices.