Border Construction and Right of Way - Experiences

Hello experts,

Question about my property (the right one):
Green is a shared right of way. On the left is a neighbor's house, 2.5 stories. I had thought about converting the garage into living space, but it is actually not possible because of boundary construction.
Because of the pathway (completely on the neighbor's side, red is a 4m wall) and the small distance of the neighbor's house to the south, the question arises:
Is there still a chance to convert the garage into living space? The idea being: if the neighbor does not comply with the boundary, do I not have to either?
Both buildings are certainly > 50 years old.

Thanks for the help,
best regards
Rüdiger

Isn't there still a chance?

Probably not. At least not ...

According to the motto: Neighbor doesn't keep to the boundary, so I don't have to either?

If you want to change something on the existing structure - I assume it is not illegally built there - you have to comply with current building regulations. A living space on the boundary (in your plan even overbuilt) is only permissible in closed development or with attachment security. The former does not apply, or is there a development plan? If house no. 8 ends with a firewall, a deviation according to §56 State Building Code could be considered. However, a licensed building professional has to inspect this on site.