Did you actually try using Excel on your phone? (The Microsoft 365 app is free, you don't need a subscription to use many features of the mobile Excel app.)
The cells are displayed at a size that is comfortable to read on a phone (which means you need to scroll). When you click on a cell, you get two handles (top left and bottom right) to grow/shrink the selection. On double-tap, a small popup toolbar appears, where you can select Fill, which makes the handles control the usual Excel filling feature. The cell headings have handles to make the cells wider. It just works, and while there are no macros, and some other advanced things might be missing, it's pretty good for most typical editing.
The cells are displayed at a size that is comfortable to read on a phone (which means you need to scroll). When you click on a cell, you get two handles (top left and bottom right) to grow/shrink the selection. On double-tap, a small popup toolbar appears, where you can select Fill, which makes the handles control the usual Excel filling feature. The cell headings have handles to make the cells wider. It just works, and while there are no macros, and some other advanced things might be missing, it's pretty good for most typical editing.