Basically: In some countries, the pledge is with the constitution or the people, but in others (like constitutional monarchies), its a pledge to the (constitutional) monarch and their successors.
What is your opinion on this loyalty pledge? Do you believe it’s a reasonable request?
(For context: My mother and older brother had to do the pledge to gain [US] citizenship so the idea of deportation isn’t looming over our heads. I didn’t have do it because I was under 18 and my mother’s citizenship status automatically carried over to me according to the law.)
That’s like saying it’s not a big ask to become a part of some random family.
What OP meant is that it’s not a big ask to be loyal to the country you’re becoming citizen of.
Following your analogy, it wouldn’t be a big ask for a family adopting you that you swear to protect the interests of said family (health, wealth, well-being, affection and safety).
If the smoke alarm starts beeping and you run away from the family house without even looking back and making any attempts to make sure that everyone got out safely, then you wouldn’t be a good family member.