We present the results of NESSI speckle imaging follow-up of 54 candidate planet hosts in K2 Campaign 10. These imaging results reveal 4 close companions, suggestive of false positive scenarios. Out of an initial set of 72 planet candidates, we statistically validate 44, due in large part to the high angular resolution of NESSI contrast curves, which typically rule out companions down to delta-mag ~ 4 at ~0.2 arcsec. The resulting validated planet sample contains ultra-short-period planets, planets in the Earth to Neptune size regime, and multi-planet systems, many of which are good targets for follow-up characterization studies via precision radial velocity measurements. We have continued this work with follow-up observations of candidate planet hosts from the TESS mission, and present preliminary results. Instruments like NESSI play a critical role in the discovery of new planets, and will continue to do so now in the TESS era and beyond.