can only speak from my personal experience, I have made a scratchpad app within Odin and it was the first language that I picked for because I wanted C-esque speed and gui libraries being built in and I even used LLM's to write the whole thing to see LLM's capabilities.

After a lot back and forth though, it was able to make it. I might link it but my point is that calling Odin niche might be same as calling every C alternative niche including Nim,D etc. You might be surprised by Vala as well!

I wanted to test Odin language and I think that its a decent language. My hiccups were in writing the glue code for taking file dialogs and another being on how to have more flexibility but it was able to connect with objC as well, but the fact that I was able to make it still impresses me to this day and I still use this tool. And after thinking of all programming languages, I ended up deciding Odin because of the things that its good at and I just wanted things to work with more simpler choices.

I just wanted to give a personal anecdote and I think that Odin could be considered a valid C competitor especially for GUI projects. I can't talk about the popularity aspect of it that much though as what feels popular to me depends on which communities I am part of and from my part using Odin and even joining their discord, it had already felt like a popular language to me (personally) at least