There is not a textual basis for the flood being "global" as opposed to local. All such bases are the result of two misconceptions:
Thinking that because, in English, the word "earth" means both soil, and planet earth, that the Hebrew word "eretz" must have the same two meanings. The Hebrew word "eretz" just means "land", as there was not a single word, let alone a conception of "planet earth" at the time Genesis was written. Thus it is always risky to translate eretz as "earth" if there is a risk that english readers will think the word is referring to "planet earth" rather than to "land".
Thinking that quantifiers in the narrative texts of Hebrew are to be understood in scientific terms rather than narrative terms. That is a Hellenistic view of the world that is not appropriate to superimpose on pre-Hellenistic texts. E.g. when I say "I threw a party and everyone came", that is a narrative statement where "everyone" is understood to quantify over all the social people in my life that could come to such a party, or all the people previously mentioned in the narrative. It does not quantify over all people on earth, or all people past, present, and future, or all sentient beings in the universe, etc. All narratives have a certain stage. In that stage, "land" refers to the land of the stage. "heavens" refer to the sky above the stage. The stars are viewed as lights illuminating that stage. "All the nations" are nations that come into play in that narrative. Etc.
In short, quantification has to be interpreted as over a specific narrative setting, which is not going to be "planet earth" as there was no notion of "planet earth" at that time.
For example, look at the famine of Joseph, which uses very similar language to Noah's flood:
And the famine was over all the face of the earth [kol pene ha eretz]: And Joseph opened
all the storehouses, and sold unto the Egyptians; and the famine waxed
sore in the land of Egypt. And all countries [kol ha eretz] came into Egypt to Joseph
for to buy corn; because that the famine was so sore in all lands [kol ha eretz].
So we have three uses of the quantifier Kol ("all") and three uses of eretz ("land") yet the action is only taking place in Egypt and Canaan. But that is the stage of the story of Joseph and his family, which is the account being described here. It is not true that all countries on the planet came to Egypt, or that there was a famine on the entire planet earth.
And we don't need to establish some creation institute to argue that representatives from Central America, Native Americans, and Japanese visited Egypt to buy bread, because we understand that "all the land" and "all the countries" refers to Egypt and its environs, not to the planet earth.
Yet for some reason when it comes to the flood, suddenly everything has to be interpreted in Hellenistic terms and now every single country does need to come into play and a lot people spend a great deal of effort on "proving" Noah's flood but very few seem to be bothered by proving Joseph's famine.
Now I'm not saying that this proves Noah's flood was local. Only that there is no textual proof the flood was global simply because there are no universal quantifiers in the language of Genesis. All quantifiers are relative to a certain stage on which the action was happening.
This also includes the creation account, e.g. God is credited with creating "the sky and the land". He is not credited with creating a planet, per se. The directions of creation as described are vertical -- above and below. Not horizontal. All the action is happening from a certain stage, and all the quantifiers need to be understood with respect to (or from the point of view of) that stage. Much (but not all) of the difficulties people face when trying to reconcile Genesis with modern science is due to their attempts to treat Genesis as a scientific book rather than a collection of narratives, with quantifiers appropriately scoped to each account.