For macOS, native historically (OS X onwards) means Cocoa and Objective-C. Swift and Swift UI are the new kids on the block. I haven't dabbled with them much, but my two cents is Swift is a lot more complicated than Obj-C and Swift UI is less mature than Cocoa. But as I said, that's just my two cents. Your mileage may very.
For Windows, Microsoft has a history of releasing a new UI technology and then deprecating it. Their latest toolkit is WinUI 3. Given Microsofts dedication to backwards compatibility I think you could pick any of their toolkits, even the WinAPI. I should mention that WinUI 3 is an oddball because Microsoft is not shipping it with the OS, but rather vendors (you) must ship the toolkit with your app.
For Linux, the two most popular UI toolkits are GTK and Qt. But in truth Linux is just a kernel and it is the distro that decides what toolkit is "native". Maybe consider which distro(s) you'll target rather than treating Linux as a monolith.
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For macOS, native historically (OS X onwards) means Cocoa and Objective-C. Swift and Swift UI are the new kids on the block. I haven't dabbled with them much, but my two cents is Swift is a lot more complicated than Obj-C and Swift UI is less mature than Cocoa. But as I said, that's just my two cents. Your mileage may very.
For Windows, Microsoft has a history of releasing a new UI technology and then deprecating it. Their latest toolkit is WinUI 3. Given Microsofts dedication to backwards compatibility I think you could pick any of their toolkits, even the WinAPI. I should mention that WinUI 3 is an oddball because Microsoft is not shipping it with the OS, but rather vendors (you) must ship the toolkit with your app.
For Linux, the two most popular UI toolkits are GTK and Qt. But in truth Linux is just a kernel and it is the distro that decides what toolkit is "native". Maybe consider which distro(s) you'll target rather than treating Linux as a monolith.