There is also a Github repository keeping track of all the load-testing tools out there: https://github.com/denji/awesome-http-benchmark You will probably find something that will fit your bill.
I do not understand though why it is of any relevance what language the application is written in. Yes, Go and Rust indicate a certain speed and novelty but you can write fast applications with good UX in other programming languages too (and bad ones in Go and Rust).
Yes I don't mean to dismiss all other languages I just happen to only have these two runtimes and few others and I'm currently having problems with Java runtime which result in me not being able to run JMeter. Plus, if it's open source it can benefit me because these are the two languages I practically use.
I found it a good middle-ground between DIY tools like "hey" and the likes of JMeter and K6.
LoadForge is really just a frontend for Locust [2] behind the scenes so all tests are written in Python which might not fit your requirement for Go/Rust, but it's affordable and quick to get started with.
Take a look at goreplay. https://github.com/buger/goreplay/wiki
