Apple Watch for my son, who doesn't have an iPhone to pair it with?

I have an old Apple Watch Series 5 with GPS + Cellular that I hardly ever use anymore and I'd like to give it to my son for his 12th birthday in about a week from now. I like the idea that he can wear the watch around town and use the cellular feature to call me whenever he needs me, and that I can track his location whenever he is wearing it. The thing is, he doesn't currently own an iPhone.

Is there some workaround here that would allow him to use without having a phone to pair it with? Or is there some way for him to pair it with my phone where he wouldn't get phone calls meant for me on my cell number, or receive text messages mean for me, etc? Can't he just pair it with his iPad or something?