Is there something wrong with official ext_loader.c which is autogenerated from spec?
Neither me nor google know anything about an 'official' ext_loader.c, any link?
And isn't it as simple as Type* proc = vkGetInstanceProcAddr(instance, "proc") ?
No, then you just would have the entry point to vulkan magic, but you still need to load all the other function pointer. Besides matching their signature in odin lang you also need to translate all structs/unions, among other tasks.