Yep, they can see the glow at the source for your typical LED illuminators from the 790s-well into the 900nm range. All of the LEDs seem to emit a tiny fraction of visible light and so the source glows, but to see it, you have to be looking at it. They do not see the projected light, however.
How hogs react to it is variable. Most don't care and I have a bunch of videos that show this. Some freak out when there is something new in their environment such as when you are ambushing hogs for the second night in a row at the same location with a horde of hunters, LOL. BTW, where are the vids from the first night, TLM?
Generally, LED IR illuminators range from 790-930 nm. The lower the nm, the closer you are to the visible spectrum and the greater the projection of light as seen through NV for a given amount of power. If you put the same amount of power on a 930nm illuminator, the range projected as seen through NV is greatly reduced. If you use an IR filter in an incandescent light or xenon light, the range will be comparatively abysmal. High nm lights are best for very short range illumination. Around 850 nm seems to be about the best compromise of good range and most usable nm.