Why not have internal OIS on a phone?
After all, there are plenty of examples out there. Even Canon now offer internal OIS on their latest full frame mirrorless R5. Many of their small snappers have it. Sony (where many phones get their imaging chips from) have had internal OIS on most of their models for years. There are many other examples including Panasonic (another source of imaging chippery), Fuji and just about anyone else that makes cameras worth having. I'm sure Nikon will catch up soon :-)