The listeners are the linking generation.
They’ve seen God’s acts: the sea, the water from the rock etc etc.
They are the ones who must remember God’s character for the next generation in the New land.
It’s a multi chapter sermon on the love God command and it’s flip side: if they don’t love God, the land will be taken from them.
Moses has, with example after example, and with increasingly inspirational rhetoric, encouraged and warned the people about keeping God in their hearts.
It’s sad in context to recall how literally the Israelites would take the commands to keep the law on their gates and foreheads, considering it’s an impassioned plea about keepin’ it real.
The first thing they are to do in the holy land is climb two mountains and on one proclaim the blessing of loving God, and on the other the curse of not loving him.