Hey, Anna,
It's not just about the backrest; there should also be enough space to the top of the canopy to fit a tall child in a lasting way. I think the TFK Dot 2 with 48cm seatback could work, it is durable and goes over terrain as well. The Valco Trend is light and incredibly spacious and could actually be your best bet - the fold is a bit larger. However, it should fit a VW Golf. You may look for a pre-owned, too, if it's more expensive where you live.
A Kinderkraft Grande is spacious and budget-friendly, though the quality is lower and also the fold is not the smallest but should fit your car boot too.
From the smaller, travel buggies, maybe a Recaro Lexa or the Kinderkraft Nubi could work, but these ultra-compacts will definitely be less roomy.