If you on occasion hike without the pack on I would carry it on your person. But if you always have the pack with you, I see nothing wrong with in in the pack.
Or do both, have it in the pack, but if you do some wandering without the pack have a way to clip it onto your belt.
When I go out on multi-day trips, I'll usually carry a small daypack in my overnight pack. The PLB stays with me everywhere I go either in the main pack or the daypack. The only exception is around camp. If I'm just going to get water or maybe look at the stars or some such, I won't take a pack with me. These are the times I'd worry about not having access to my PLB, although I do always wear a whistle on my survival necklace. Even if I fell down an embankment or something, I could blow on the whistle and hopefully attract the attention of others in my group. The whistle wouldn't work well on my occasional solo hikes, which is where I'd really want to have the PLB with me at all times.
Maybe a small fanny pack? My PLB is an ACR Aquafix, which is a bit bulky for a pocket but might work well with a fanny pack.
HJ