You should probably check out Wargroove on Steam. It's very close to the Advance Wars games in terms in terms of mechanics.

They remade them for Switch. Some people claim Wargroove is a spiritual successor but I didn’t like it nearly as much

There's a not-modern variant for pc/web at https://awbw.amarriner.com/ and a modern not-pc/not-web variant for the Nintendo Switch.

My wife asked the same question when I was restoring the GBA I found in the closet, so I set up an emulator with the ROM on her phone. Less storage space than most apps and doesn't need ads or tracking.

Lost Frontier on mobile is good. Better than Wargroove imo. It really feels like the original Advance Wars in its simplicity. Just in a Western cowboy setting.

I’ve had Warside wishlisted on Steam for a year now, as it looks to be just that. And when I looked it up just now to double-check the name, looks like it’s coming out next month! Fingers crossed.