While the PlayStation DualShock design has won its share of fans over the years, the Xbox controller is the stereotypical image of a gamepad in many people's minds (much like the Discord logo). So it makes sense that there are many more options for mobile games of this form, and the best of them belong to SteelSeries: Nimbus+ for Apple devices and Stratus+ for Google devices (Android and Chromebook).
Both controllers are for the most part identical. They have shoulder buttons and triggers, the d-pad is the same, and they both feature durable phone mounts that let you attach your device to the top—the type that locks automatically. Unlike the more generic company's clamp, the one SteelSeries ships with both controllers won't get in the way while you're setting up your phone.