quote below for reference:
At that time Jesus went through the grainfields on the Sabbath. His disciples were hungry and began to pick some heads of grain and eat them.
When the Pharisees saw this, they said to him, “Look! Your disciples are doing what is unlawful on the Sabbath.”
He answered, “Haven’t you read what David did when he and his companions were hungry?
He entered the house of God, and he and his companions ate the consecrated bread—which was not lawful for them to do, but only for the priests.
Or haven’t you read in the Law that the priests on Sabbath duty in the temple desecrate the Sabbath and yet are innocent? I tell you that something greater than the temple is here.
If you had known what these words mean, ‘I desire mercy, not sacrifice,’[a] you would not have condemned the innocent.
For the Son of Man is Lord of the Sabbath.” - Matthew 12
I guess I'd also add that in the general Christian view, the specific, older-testament-era laws around the sabbath had a meaning, but they were really pointers to higher laws and concepts rather than, or possibly in addition to, being materially meaningful standalone practices. And as you rightfully point out, those "little laws and practices" were also subject to a higher law. I remember when I lived in Japan, I was working outside as very hungry young missionary one day and a kind old woman grabbed some fruit and a bag of chips off of her family altar and gave them to me, demanding that I eat. This had similar significance to me and is an experience that's very close to my heart.
IMO sabbath observance a great practice. There are few things like the feeling of a day that is uninterrupted by work concerns. And going beyond the limitation to what we _don't do_ on that day, it's also a day that's set aside for meditation, big-picture thinking about life, spirituality, and connection with the universal. In the past I let it slide a lot more than I do now, but in the past I was also a much less-healthy workaholic.
It's important to distinguish Rabbinical law from biblical laws in this case. There are very few biblical laws about how to keep the sabbath.