This is cool, but if you extensively use cloud-native components where the bare metal is abstracted from you (eg: noSQL databases, pubsub, storage buckets, cloud functions, etc) it's very rare you're paying a fixed sum, compared to if you're doing stuff the old school way with a virtual machine assigned 2GB of RAM and 2 CPUs where it's more obvious that you're paying a fixed sum.

I ran the tool on one of my projects' terraform files and it came out with a huuuuge list of infrastructure along with summaries like "Monthly cost depends on usage: $0.026 per GiB". But the grand estinated total cost of this entire project was: $0 per month...

That's the tricky bit, you can't really estimate the cost of this stuff without doing napkin maths on usage. I don't really see how you'd be able to improve this situation, either.

I'm glad someone is trying to bring better transparency to cloud costs. I think this would be a cool thing to add in a terraform CI pipeline. For example: you could allow your devs to be more agile when prototyping by allowing them to change terraform in dev without approval, assuming the MR doesn't add more than $XYZ in costs per month.