If you keep any of the old law, you are a debtor to the whole law (Galatians 5:3).
That's quite different from what the text says. The text says the man who accepts circumcision is obligated to keep the whole law. This is because circumcision was the initiatory ritual for the Old Covenant.
Your statement - if you keep any of the old law, you are a debtor to the whole law - is patently absurd. If I sleep only with my wife, that does not obligate me to sacrifice a passover lamb. The moral law is still binding. Now, as to whether the Sabbath was moral law or ceremonial or civil law is another question entirely; but your statement is self-defeating.
Do you celebrate the Sabbath as is commanded in the Old Testament?
I do ... "Remember the Sabbath ... to keep it holy" ... as commanded in the Old Testament.
If you keep any of the old law, you are a debtor to the whole law (Galatians 5:3).
Do you keep the command to ... "Have no other gods before Me(God)." ?
Everything I choose to do (or not do) ... is, strictly, ... because I desire to please God.
Nothing I do is, in any way, ... an attempt to keep the Law, ... for I know that I cannot keep it perfectly.
OTOH, ... it sounds like you are saying that my choosing to "Remember the Sabbath" ... or to worship with the accompaniment of musical instruments ... somehow abrogates the New Covenant of Grace.
Is this what you are saying ?John 1:17 For the law was given by Moses, but grace and truth came by Jesus Christ.