God deemed the seventh day of rest because he rested on the seventh day.
Hebrews 4:3-4 likewise reminds us that God's rest is full-time, and that we enter into God's own full-time rest.
Agreed. . .and those instructions are found in the NT.
In terms of being the "official day of rest," Sunday is better in the U.S. because it is generally considered not a work day, as Saturday often is.
Hebrews 3:7-4:11 presents God's own full-time rest to the people of God in the salvation rest in Jesus Christ, from our own works to save, and in Christ's work which saves.
Lets quote some of these passages to see if it says what you're trying to make it say:
Hebrews 4:3 For we who have believed do enter that rest, as He has said:
“So I swore in My wrath,
‘They shall not enter My rest,’ ”
although the works were finished from the foundation of the world. 4 For He has spoken in a certain place of
the seventh day in this way: “
And God rested on the seventh day from all His works”;
Does not say this....
Hebrews 4:3-4 likewise reminds us that God's rest is full-time, and that we enter into God's own full-time rest.
Instead, it says the seventh day is the day God ceased from His works and Hebrews 4:10 reminds us that we must cease from our works the same day God did from His- on the seventh day- not "everyday". You are adding words that are not there.
Hebrews 3:7-4:11 does not say God's rest is full-time either and we no longer have to keep the Sabbath commandment. This is a warning to those who do not obey God and are in rebellion and disobedience to not harden their hearts to God, what there were disobeying was the Sabbath.
Hebrews 3:15 while it is said:
“Today, if you will hear His voice,
Do not harden your hearts as in the rebellion.”
It does not say "today" is the day of rest. It clearly said today if you hear His voice- do not harden your heart.
Hebrews 4:6 Since therefore it remains that some
must enter it,
and those to whom it was first preached did not enter because of disobedience,
This is a warning we should be careful not to enter into His rest by disobedience and hardening our hearts.
What were they disobedient to whom it was first preached and did not enter into Christ rest?
The Sabbath. Which is what Hebrews 4 is about, keeping the Sabbath Hebrews 4:9 just as God did Hebrews 4:4, Hebrews 4:10, not spiritualizing it so it's no longer a commandment of God. This is not a teaching of the scripture and is a man-made teaching leading people away from God.
Ezekiel 20:13 Yet the house of Israel rebelled against Me in the wilderness; they did not walk in My statutes; they despised My judgments, ‘which,
if a man does, he shall live by them’;
and they greatly defiled My Sabbaths. Then I said I would pour out My fury on them in the wilderness, to consume them.
Hebrews 3 and 4 is a warning that we shouldn't follow the same path of disobedience
Hebrews 4:11 Let us therefore be diligent to enter that rest, lest anyone fall according to the same example of disobedience.
I will leave this scripture to those who has ears and want to hear God's Truth as it is plain to see.
I won't further respond on this topic, because it typically ends with us just repeating ourselves and I think the scriptures speak for themselves and you have not provided one scripture where it plainly says "everyday" is the day of rest or we choose which day to rest, which is the opposite of Hebrews 4:4, Exodus 20:8-11 and Genesis 2:1-3.