The Sanhedrin has been recreated in Israel; the Temple Institute has made/is making Temple implements, priestly garments etc., all for the building of the Third Temple, and restoration of Temple Worship during the Tribulation. The Jews will believe it to be a valid, “real” Temple and their rites to be genuine — up to the time of the Abomination.
What does Scripture suggest will be God’s reaction/response be to Temple rituals performed in good faith by the Jews prior to the Abomination? Will He honor the sacrifices, etc. in any way? Will He indicate displeasure or rejection of the sacrifices in any way?
In order for the anti-Christ to desecrate the Temple, it will have to have been holy previously. So yes, the sacrifices will be acceptable. Remember, this will be the final 7 years of the Age of Law, so things in Israel will be very similar to Old Testament times, at least from a religious standpoint. The nation will officially be in covenant with God, and will be governed by the Sanhedrin according to Old Testament Law.