Kagura would need signature yes, and unless the beast is actively in use you would have to be almost right up their face with prolonged focus to pick the beast out anyway, as seen with Karin.
Sage mode, signature yes, however if beast isn't in use the ability to pick out the host anyway is far more questionable, because senjutsu hax isn't answer to everything.
Byakugan's a mess because there is no unified consensus of its 'insight', much less range. However I will daresay there is no way you'd find a host quickly, especially without signature and beast not being in use, since even if the eye has massive range its not like you are constantly aware of everything happening in that entire kilometers long range. Like a shorter range I might understand the 360 from, but there's no way your brain would handle constant awareness of every single detail at like 10+ KM range, especially when at several points in the series its been shown hyugas still focus on specific things at even longer ranges.
Be those as they may, difference is you need time/effort and most likely signature in all of the above. Telescope will find them no matter what, wherever they are, unless their chakras basically shut off (aka untrackable) or they're in a location somehow sensing proof otherwise.