The big play are the USA's M2 Bradley and Stryker vehicles, which will effectively mechanize a few battalions of the Ukrainian infantry. Each Bradley can hold 6 troops, each Stryker can hold 9.
The problem: mechanized infantry needs Tanks for support. Early on, France's AMX-10 RC recon vehicle (aka: a light vehicle with a big tank gun on it) was being considered, but it looks like proper tanks have been decided upon.
France is sending those AMX-10 RC vehicles anyway.
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By mechanizing the infantry, they aren't going to be riding in Toyota trucks around the battlefield anymore. They'll have large 25mm Autocannons, medium armor (M2 Bradley) or light armor (Strykers) to protect them.
M2 Bradley have advanced optics that can see 3000 to 4000 meters at night, and gun computers (fire control systems) that can accurately make shots at those distance. And rockets just in case it comes across an enemy tank (though its #1 routine would be to call a friendly tank for backup in that situation).
Ukraine has a significant number of brave troops who are making due with what they got. Just civilian cars and trucks right now. Giving them a proper battlefield taxi (aka: M2 Bradley, Strykers, or Humvees) is a huge step up.
Ukraine does have a mechanized infantry core that's already done some pretty amazing offenses. But Ukraine obviously needs to make that core larger and stronger for the upcoming offensive.