Krita 3.0 actually has a Paint Tool SAI-compatible input sheet shipped by default.

Hide Selection, Reset Rotation are currently not available via the Toolbar configuration, you’ll need to use the shortcuts Ctrl + H and 5 to toggle these. (Though, on smaller screens this will cause all the things in the Brushes and Stuff Toolbar to hide inside a drop-down to the right, so you need to experiment a little).

You can do the same for Redo, Deselect, Invert Selection, Zoom out, Zoom in, Reset zoom, Rotate left, Rotate right, Mirror view and perhaps Smoothing: basic and Smoothing: stabilizer to get nearly all the functionality of SAI’s top bar in Krita’s top bar. When done right, the Undo should now be sandwiched between the save and the gradient icon. There, toggle Hide text when toolbar shows action alongside icon to prevent the action from showing the text. Select the action to the right, and click Change text. Then select the action ‘undo freehand stroke’ and drag it to the right. Then, you can type in something in the left column to search for it. There are two toolbars, but we’ll add to the Main Toolbar. Go to Settings ‣ Configure Toolbars… menu item. You can also put these commands on the toolbar, so it’ll feel a little like SAI. You can use the Overview docker in Settings ‣ Dockers to quickly navigate over your image. Use the 1, 2 or 3 keys to reset the zoom, fit the zoom to page or fit the zoom to page width. You can use the + and - keys to zoom out and in, or use the Ctrl + shortcut. But you can also have more sophisticated rotation with the Shift + Space + drag or Shift + + drag shortcuts. There’s a couple of possibilities here: either the 4 and 6 keys, or the Ctrl + shortcuts for basic 15 degrees rotation left and right. Unlike SAI, these are tied to keyboard keys. Krita, just like SAI, allows you to flip, rotate and duplicate the view. This section goes over the functionalities that Krita and Paint Tool SAI share, but shows how they slightly differ. Introduction to Krita coming from Paint Tool SAI ¶ How do you do that in Krita? ¶

Paint tool sai ink brush