How are the extended and low-surface brightness halos of early-type galaxies built up, and which role does their environment play in their evolution? While resolved stellar populations from deep HST imaging are excellent tracers of nearby galaxy halos in pencil-beam fields, it is challenging to use them as tracers of extended haloes in galaxies or of the diffuse intracluster and intragroup light (IGL) at large spatial scales. Instead, at these distances, Planetary Nebulae (PNe) are a viable alternative. They are commonly used to trace spatial distribution and kinematics of the halo and intracluster light at distances of up to 100 megaparsecs. In my talk, I will focus on two non-isolated early-type galaxies: M49 in the Virgo Subcluster B and M105 in the Leo I Group. Since the Leo I group lies at just 10 Mpc distance, it is ideal for comparing results from resolved stellar populations with the homogeneous constraints over a much larger field of view from the PN populations and deep widefield photometry. In M105, we have — for the first time — established a direct link between the emergence of a metal-poor halo as traced by resolved red-giant branch stars and the presence of a PN population with a high specific frequency. This result confirms our earlier inferences, e.g. for M49 in the Virgo Subcluster B, that metal-poor halos and intra-group light are predominantly traced by PN populations with high specific frequencies.