So we agree that Paul became all things to all men so that by all possible means he might save some.
The nature of the Sabbath rest in Heb 4:1-13 is spiritual, it is rest in Christ.
It is rest from our own work to save, and rest in Christ's work which saved us.
Christ is the fulfillment of the Sabbath, set apart (sanctified) and given for rest (Ex 23:3; Dt 5:14),
which is why we find the NT Christians assembling on the day of Christ's resurrection, the Lord's Day (Ac 20:7; 1Co 16:2; Rev 1:10).
Salvation is the Lord's! (Rev 7:10)
Paul, who received his revelation from Jesus Christ personally, in the third heaven (2Co 12:1-5), was emphatic about work NOT being
involved in justification/salvation, because in the third heaven he was given to understand why God was so emphatic about the
Sabbath-rest (Ex 31:14-15, 35:2-3; Nu 15:32-36; Jer 17:21-22, 27)--it was a prefigure/sign (as was most of the OT legislation)
of God's everlasting salvation rest in his Son Jesus Christ's atoning work on the cross.
And God is emphatic about salvation rest, prefigured in his OT Sabbath-rest, because
Salvation is the Lord's!. . .all the glory goes to him. . .we do not, and cannot, contribute anything by our work, we must rest
in his work in Jesus' atoning sacrifice.
That is the NT revelation of Heb 4:1-13--a spiritual Sabbath-rest in Jesus Christ for the people of God.