If you're stretching a budget, buying dried beans and lentils in bulk is probably your best move - protein and fiber for pennies compared to fresh stuff. The UN report is basically putting numbers to something people already feel, but what's worth noting is the inequality within countries matters almost as much as between them. In the US or UK, you might have food deserts in certain neighborhoods where a family genuinely can't access affordable fresh food even if they wanted to, while someone ten minutes away has farmer's markets and whole foods stores. That's different from just "healthy food costs more" because it's about access layered on top of price.
The thing that strikes me about these reports is they usually frame this as inevitable, but food systems are actually pretty flexible if there's political will. Some countries have started subsidizing produce differently or incentivizing grocery stores to stock affordable vegetables in underserved areas. Whether that scales globally is another question, but the point is this isn't some immutable law of economics - it's about how we've structured agriculture and retail.
As for where prices go, honestly I'd expect them to stay weird. You've got climate stuff affecting crop yields, supply chain issues that come and go, and the fact that processed food is artificially cheap because corn and soy are heavily subsidized in a lot of places. Fresh produce doesn't get that treatment, so the gap probably widens unless something changes. Don't expect rapid improvement just from the UN report existing - these things usually need pressure from people actually demanding different policy.