Sabbath just means one out of seven. If you chose to observe a day of rest every Thursday it's the same thing.

No waggler its not. Sabbath is a Jewish thing. The ten commandments are Jewish. Keeping the sabbath is Jewish and clearly means Saturday. Sun down Friday To sundown Saturday to be exact.

There are exemptions for what is considered work. Saving a donkey in a pit even if it was a long was a long walk was still OK. Feeding animals is ok.

There's a lot more to the sabbath than just not working. Can't cook can't start a fire (no lights to be turned on) etc...
Having lived in Israel I have experienced lots of real sabbath. Everything that needs to be done is done all prior to Friday sunset. That includes leaving stoves and fires on. Elevators are set to stop at either odd floors, even floors or every floor, no driving is done unless it's absolutely necessary. Lots of people had to hotels and the Mediterranean to swim and relax. Sabbath dinners are big meals done with singing and stories. Church/worship is observed.
There's a lot more