Basically all the land is already owned by corporations or farmers with generational wealth

This is really not true. Around 15% of total -current**- farmland by area is owned by corporations. I get that you probably want to say it's often the case and that "much" land is owned by corporations, but that's not 100% the case. There are also several initiatives to help match farmers with land either to buy or rent, and even government loan programs to help folks buy their land. I know from personal experience that it's not easy, but I also know compared with actually making a living farming, finding the land is relatively easy.

** I specify current because there are many different classifications of what constitutes arable land. When it comes down to it any land is "arable" with enough effort.