Understood - possible solutions: Building a ramp, dividing the flat into different areas, removing the threshold, demolishing the house and building a new one but without thresholds.
For obstacles that should not be driven over (e.g. chair legs): Stick bumpers on the legs and raise the obstacle. For door thresholds (necessary from about 2.5 cm) there are e.g. rubber mats/rubber ramps for cars or wheelchair users. Or noble: handmade ramps made of wood....