I am running iOS26 on my iPhone 13 Pro, and on my m1 iPad Pro. It runs fine on both, but I really regret upgrading on my iPad because the new window management options are terrible. It makes me actively dislike using my iPad now, and it used to be my daily driver.
You can turn those off, no? When I upgraded it asked me which I preferred, the old or the new style, and I kept the old. I presume it’s a setting toggle somewhere.