LAPL medicals can be done by a GP
That's true, at least in theory. In practice most GP's can't be bothered with the hassle. Also, many would regard COPD as "serious" in flying terms, and so once again such individuals would find themselves referred to us AME's !
In my view most class 2's with COPD could be adequately assessed with a thorough history, thorough auscultation and a PFR. I doubt if a full spirometry would add much (though it is, of course, usually done at initial class 1's ).