The thing I can never figure out how to do is move the cursor very far, eg to the other end of a url in the address bar. Spacebar trick only moves the cursor so far. That’s mostly only useful if the text field has word wrap because you can move it up and down.
For this, first hold the spacebar to get a single cursor (address bar defaults to select all), then drag the cursor itself (not the spacebar). It accelerates to the end
An easy fix for that would be to allow a second finger to drag the text field - hold space to activate the cursor, drag the text with a second, bingo. Or let the second finger hit "jump left, jump right" targets on the blank keyboard when you're holding space (but this is more mechanically difficult at least for me.)