Went to a camping in the Laurentians in Québec (Ste-Agathe) and there were those things near some camp sites. The sites are only accessible by footpaths. No car access. And if you bring a bike, you have to walk it up a hill, so I doubt they are bike racks.
EDIT: I have sent an email to the park and they have been kind enough to reply. It's just a type of fireplace with a grate. They didn't give more info than just this. Thanks to everyone for pitching in!
OP, none of the answers here are satisfactory. Please ask the rangers and update this post because this is fascinating.
Google Lens wasn't helpful, it compares it to things like drains and fences built around old markers (it specifically thought it was a Mason-Dixon line marker which is obviously incorrect). But this is not protecting anything and not a drain.
My guess is, if it's not something to tie a horse to, is maybe it's something to put animal feed in? But that's a wild guess, I don't really think it's right. Like shove a hay bake in. But you said only accessible by walking, so I really doubt it.
It looks like a park but it's a municipal camping with a forested area for tents. I will ask the employees when I go back, but I'm afraid they may also not know. I'm also tempted to call and ask directly but this gives me a reason to make another cycling trip "in the north".
how can I make sure to not miss the update??
I hope you'll post what you learn as a new message in this community, so we all see it.
updated
Salt lick. Hunters use em for attracting animals. Takes time. You drop a big block of askt on the thing.... that be my best guess at that.
OP said there is one at each camping spot and you can see the camp fire right there. That seems very close to be a spot for a salt lick.
10/10 I jump the gun on that one. I read the words food and got way to excited.