It depends on the title, some of them have built-in voice chat like Fortnite, in that situation you can just use your Switch by plugging a headset into your Switch, be it in the headphone jack or with a audio usb dongle on the dock. I've used both and they work.
For some select Nintendo titles you have the NSO, but it's a hasstle to use.
I prefer to use a simple phone call, Whatsapp or Discord on my mobile together with a bone conduction bluetooth headset, then I can listen to both the in-game audio and voice chat at the same time.