I would buy it immediately. The trees will surely have a huge impact on the climate in summer. You have enough space to find a nice spot in the garden even in spring. And summers are going to get warmer anyway.
And for longer enjoyment of the sun on the west side, plan a balcony or a rooftop terrace. (Bet you will never use it, but will love your garden/terrace instead?)
I was on site again yesterday. Full sunshine still at 3:30 PM throughout the entire property. I think we will go for it.
PS: Kindergarten is being newly built at a distance of about 500 m, a primary school is already in the immediate vicinity, as well as a new modern EDEKA market.
Many would be happy to be able to buy such a plot (or to be offered one). If you currently have full sun on the property until 3:30 pm around the equinox days, that is more than generous. You will actually have sun almost all day in summer. Most can only dream of that. Therefore, be glad if it is somewhat subdued by the rows of trees. We currently still have sun in our apartment until sunset in the evening and in summer we still have to fear sunburn when dining outside...