This operates under a misunderstanding of what the expectation of the temple was. Regarding the expectation of the temple in original Jewish thought: In the core, standard Jewish theology of the temple, the temple is only a type of the full reality of YHWH's heavenly dwelling (vertical typology) and of the fullness of his presence at his coming (horizontal typology). So it is always something partial, not the fullness. The Old Testament foretells the coming of YHWH, the fullness of YHWH's presence replacing the partial. It can sometimes depict this as the Lord inhabiting a new temple, at other times as the fullness of YHWH's presence replacing the partial presence in the temple, and at other times as YHWH pouring out his Spirit on all flesh in replacement of the temple. And even in many of the depictions of a new temple, the description clearly goes beyond the conception of a single building to a conception of God's presence filling all the earth and all creation. For example, Ezekiel's temple in 40-48 is clearly metaphorical. Ezekiel 11:16 says that YHWH was a small sanctuary for the Israelites. But in Ezekiel 37, which elaborates upon Ezekiel 11:14-20, Ezekiel says that, through a Davidide, YHWH's "sanctuary" (same word used as in Ezek. 11:16) will be "over" or "among them" forever, thus implying that YHWH's sanctuary in Ezekiel 37 is YHWH's presence among his true people, as in Ezek. 11:16. Since Ezekiel 40-48 is an expansion or elaboration of Ezekiel 37, this is significant. Besides, unlike descriptions of physical constructions elsewhere in the Hebrew Bible (e.g., the Tabernacle or Solomon's Temple), there is no height to the Ezekiel Temple. And every other "vision" of Ezekiel is metaphorical. For example, no one thinks that the resurrection in Ezek. 37 is prophesying a literal resurrection. Rather, it's a metaphor of forgiven Israel's restoration. Why would the Ezekiel vision of the Temple be any different? That there are in-depths depictions of Temple (e.g., measurements, etc) is not weighty. Apparently it wasn't in-depth enough to include height or a roof. Besides, the "resurrection" in Ezekiel 37 is also depicted very graphically and specifically too. So, this can't be used as an argument for the temple being physical.
This is also supported by the imagery in Genesis 1 of the cosmos as YHWH's temple.
So, the offerings and sacrifices in the temple must be interpreted in this non-physical framework. I see Isaiah and Ezekiel using the past as a way to foreshadow the future. Just as there will be a new Exodus and Temple, so the sacrifices they describe tell us something about the worship of the renewed "Israel." For example, you point to Isaiah 56:7. But that the offerings and sacrifices denote prayer in this passage seems to be shown by the Hebrew participle כִּ֣י ("for"), which gives explanation to what the offerings and sacrifices signify:
"Their burnt offerings and sacrifices will be accepted on my altar; for my house will be called a house of prayer for all nations.” (Isa. 56:7)
This already should tell you something. Isaiah 66:18-21 also says:
18 “And I, because of what they have planned and done, am about to come and gather the people of all nations and languages, and they will come and see my glory. 19 “I will set a sign among them, and I will send some of those who survive to the nations—to Tarshish, to the Libyans and Lydians (famous as archers), to Tubal and Greece, and to the distant islands that have not heard of my fame or seen my glory. They will proclaim my glory among the nations. 20 And they will bring all your people, from all the nations, to my holy mountain in Jerusalem as an offering to the Lord—on horses, in chariots and wagons, and on mules and camels,” says the Lord. “They will bring them, as the Israelites bring their grain offerings, to the temple of the Lord in ceremonially clean vessels. 21 And I will select some of them also to be priests and Levites,” says the Lord.
In the context of both Isaiah 56 and 66, the topic are the "servant of the Servant." In Isaiah 53:10, it says that the Servant "sees" his offspring which he presumably gained during his life. The "offspring" do not refer to literal children, according to most scholars. After chap. 53, the figure of the individual servant is replaced by community called the “servants” in the plural (Isa. 54:17; 56:6; 63:17; 65:8, 9, 13-15; 66:14) or “offspring" (Isa. 59:21; 61:8-9; 65:9, 23; 66:22) who follow him and form a "new Israel." Thus, Isaiah 53:10 serves as a fulcrum for this entire shift in focus from Servant to "servants." In Isaiah 66, it says that YHWH will gather all nations and languages. YHWH does this by sending "some of them" to proclaim "my glory among the nations." In v. 20, it than says that these will bring the people of God, from all the nations, as an offering to the Lord! Clearly, as in the NT, the "offerings" here are preaching. Isaiah 60:7 communicates the same message. It than says that some of the people brought to Jerusalem "in ceremonially clean vessels" will be priests and Levites. Joseph Blenkinsopp notes regarding v. 21: "in the context, the only possible antecedent of mēhem (“some of them”) is the phrase the “nations of every tongue" (Joseph Blenkinsopp, Isaiah 56-66, pp. 314), and so gentiles are included in the Levitical priesthood!
Isaiah 66 clarifies how, as it says in Jeremiah, there will be Levites as many of the sand in the sea shore and stars in the sky. The gentiles will be included. The sacrifices and offerings aren't physical there either.
The NT shows how this expectation was fulfilled in prayer, preaching, hymns, etcetera, all across the world, just as the Hebrew Bible celebrates and expects all over the place.
Jesus is the Messiah,