>>> any device that has a tuner /capability of receiving a transmission attracts the need/obligation for a licence
As Murraymints states, you need a TV licence to 'install' any device which is capable of receiving TV broadcasts, irrespective of whether you actually use that facility or not.
As an analogy, in the days of VHS video recorders, some people who only had black-&-white TV sets went out and bought video recorders. As soon as they did so, they had to buy colour TV licences (even though they could actually only watch programmes in black-&-white) because their video recorders had tuners inside them which were capable of receiving colour broadcasts. (i.e. they were deemed to have 'installed' equipment capable of receiving colour TV transmissions, even though it was impossible for them to view programmes in colour).
So if you buy a TV set and connect it to the mains you're deemed to have 'installed' broadcast receiving equipment, irrespective of whether you use it solely as a means of viewing Firestick content (or, for example, solely as a computer monitor).