Regarding the pool, we already know where it will go if the plan is realized as is. The plastic pool can also be placed on a substructure so that the lawn underneath doesn’t suffer too much. Leveling a separate area for it is out of the question.
The substructure doesn’t work, the lawn will definitely be damaged, it needs light, fertilizer, and must be mowed at least once a week. You should think about that, the kids definitely want a pool in the garden somehow, and it can be placed well on a paved corner or on the terrace. 10% of the house costs seems too cheap to me now. We had a user here once who mentioned something about a six-figure sum. With all the plant planning, you also have to consider what kind of plant care you are ready for. You have planned a lot of plants, including a hedge, probably perennial beds in front, etc. Such a hedge is quite maintenance-intensive, and perennial beds, etc. also need care, so it’s not done with just planting once. So if you are not big "garden fans," I would take that into account when planting.
Best regards Sabine