That is incorrect. The commandments (the Law) were given to the Israelites, not to the Gentiles. The verse you quoted is irrelevant.
The gospel was indeed given to all, but the Law was not.
Unfortunately, none of this answers my question. The gentiles were excluded from Israel; they would have no inclination to follow Israelite ordinances.
I already addressed this.
Why would Gentiles "keep" an Israelite ordinance?
They wouldn't! They might, however, for convenience, gather with Israelites to hear the word of God when and where the Israelites gathered.
A covenant is not a "promise" though the concepts are distantly related.
Israel broke the first covenant. God initiated the new covenant in Christ's blood. We Christians are under the new covenant, not the old/first/Sinai covenant.
You might find these sites helpful for searching Hebrew terms:
Blue Letter Bible Bible Search and Study Tools - Blue Letter Bible
Bible Hub Bible Hub: Search, Read, Study the Bible in Many Languages