Isaiah 49 is reassurance to Zion that Yahweh has not forgotten her. Her walls are continuously ( tamid ) before Yahweh, like the sacrifices and showbread (v. 16). And Yahweh goes beyond the assurance of His concern to promise that Zion will be surrounded by gathered people, returned exiles and the Gentiles who accompany them from the islands (v. 18).
He swears that Zion will put “all of them” on like ornaments (v. 19). All of what? Perhaps we are to interpolate “treasures” or somesuch, but gramamtically the antecedent is the “all” that gather to Zion, the people. Zion will not be adorned only with the stuff that is brought to her; Zion will be adorned with those who bring the stuff.
These adornments are bound on Zion as jewels on a bride (v. 19). And, again, these ornaments are people. Like the final Bride of Revelation 21-22, Zion will be a bridal city decorated with the tribes of Israel and the nations.