I have this kind of training planned
-60m ramp 70-110% (178-280w)
How to perform it in Garmin Edge 1040? Seriously is it such a problem to add to edge an option for such a workout!

Because it's more convenient and that's how wile training platforms do it. Zwift, MyWhoosh, Wahoo, and others.
One line that can be interrupted with one press of the lap button:
- 60m ramps 70-110%
Counter a dozen lines:
-90s 70% (178w)
-90s 71% (181w)
-90s 72% (183w)
-90s 73% (186w)
-90s 74% (188w)
-90s 75% (191w)
...
And one more thing, Garmin has a limited training step limit of 50.
Spent a couple weeks with Garmin support regarding an ERG ramp & Edge830, sent ERG, FIT, and device file system files.
Even sent screenshots from 830 & my Bolt. Bolt displayed the same ERG interval as a ramp, 830 didn’t.
Final outcome from support, ERG ramps are not supported.
(Full disclosure, trainer is a Kickr, didn’t test any other brand)
I’m forced to use my Bolt indoors.