Learn Hardcore Norwegian: Snøen blir måkt tidlig om morgenen. - The snow is cleared early in the morning.

Blir + past participle expresses a dynamic or processual passive, focusing on the action of shoveling itself. It tells us that someone regularly shovels the snow each morning.
By contrast, er + past participle describes a static result:

Snøen blir måkt tidlig om morgenen. “The snow gets shoveled early in the morning.” (you regularly shovel it)
Snøen er måkt. “The snow is shoveled.” (it’s already in a shoveled state)

What is the function of om morgenen in this sentence?

Om morgenen means “in the mornings” and marks a habitual or recurring time frame. It indicates that the action (shoveling) happens regularly every early morning, not just once.

Can we also use the -s passive instead of blir here?

Yes. The s-passive is very common in everyday Norwegian. You can say:
Snøen måkes tidlig om morgenen.
This has exactly the same meaning (“the snow is shoveled early in the morning”) but is shorter and often feels more colloquial.

Why is snøen in the definite form here?

Using the definite form snøen (“the snow”) shows you’re referring to a specific snowfall (for example, the snow on your driveway). If you were talking about snow in general, you’d use the indefinite form snø: “Snø er vakkert.”

What does måkt mean, and how is it formed?

Måkt is the past participle of å måke (“to shovel”). Since å måke is a weak verb ending in -ke, its past participle ends in -t. In passive constructions like blir måkt, you always use the past participle form.

Why do we say om morgenen instead of på morgenen? And what about days like mandag?

Norwegian uses different prepositions for parts of the day versus days of the week:

Parts of the day: om morgenen, om kvelden, om natten (“in the mornings/evenings/nights”).
Days of the week: på mandag, på lørdag (“on Monday”, “on Saturday”).
If you want to refer to one specific morning (not habitual), you’d say i morges (“this morning”).