Not exactly the same, but I switched from Insomnia to Hurl.
https://hurl.dev/
If you're looking for a tool with a nice UI, Hurl might not be the ideal choice. We're focusing our tool on CLI usage and CI/CD integration.
On the other side, Hurl is a pure Open Source tool, we're not VC backed. The tool is given to the community by a big French telco, Orange, which use it and has no intention to be in the software business. In a word, there is less chance for Hurl to fell into Postman or Insomnia fate...
[1]: https://hurl.dev