Differential flux of the candidate TeV halos discussed in the text, compared with the differential sensitivity for extended (R_src = 0.5°) sources of the next-generation IACTs. The LHAASO-KM2A differential sensitivity is also reported, showing its capability of unveiling all of the hereby investigated sources provided these are in its field of view: specifically this is the case for the HAWC candidates and PSR J0359+5414. The measured size of each source is also reported in the legend, as extracted from TeVCat. The shaded bands are computed from the 1σ spectral uncertainties (slope and normalisation) also provided there.