Great point. While not everything is appropriate to share in response to someone else's "Show HN" post, I've definitely seen (and appreciated) others linking similar projects. It usually is in the context of saying something like:

- I tried this too, and can appreciate that you solved way harder things than we expected to have to deal with - I had this idea too but like your execution

I think it's very fitting, especially since we are celebrating not just the idea, but the execution that someone did to be able to show it off here.