no, the HDX or the RealPresence GroupSeries cannot be used for Teams natively. If you have these devices you should work with a Poly reseller to look into the RealConnect service.
It is free until June and they can advise you of pricing. This will allow the devices to dial into Teams meetings.
Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels. Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's