Carrying a SPOT or similar is really a personal choice. I mostly go solo and prefer to take one (inReach). But the CT is plenty busy in July/August so it’s not like someone won’t come along for any significant length of time. Speaking of which, you’ll have a lot of opportunity to talk to, and hike with, friendly people on the trail. Might be a better way to pair up, for some or all, of the hike, then to commit to doing the whole thing with someone you don’t know and may not match up well with. Enjoy the hike if you go.