Kindle for Mac

I have kindle for Mac version 1.33.0 and updated 1/3/2022 running on Monterey M1 Macbook Air.

There is a function in the kindle app under File/Import PDF... to open a dialog box to select a pdf file. Selecting a pdf puts it in the library on my Macbook Air but it does not sync to my iPad or my Kindle device.

Should all three devices sync pdf's? Online suggestions say to transfer via USB (which is not available on M1 laptops) or by emailing the pdf to my Kindle email address. Other options?