The green line numbers are only shown in Studio, they are not exported to the gcode file. If you use a utility like Notepad++ you can “overlay” line numbers onto the gcode file went you open it. You would need to sync the line numbers by adjusting them in Notepad++.
They appear but only at the start of a layer. You cannot place them via Bambu Studio at points during the layer.
That being said, you can manually add them via the method I previously outlined.
I added the 2 pauses and saved the gcode.3mf file and then reopened it in Bambu Studio. I have run this file on one of my printers and it acted exactly as expected. It printed the layer up until the pause, paused (dropped the bed and positioned the head over the poop shoot) and prompted the user to resume. I resumed and it continued printing the layer till the next pause and repeated how it acted on the first pause.
Because editing gcode isn’t something the majority of users should/need to be doing.