Relative pointers are great in memory map data structures. All pointers are relative to current offset. That way it's almost always also possible to get away with just 32-bit pointers -- you get +- 8 GB range.
A library that can do that in Rust would be great.
Only if you use byte aligned relative pointers. For data structures you don't need better than 32-bit aligned pointers. So you get +- 8GB relative offsets. It's not all that unreasonable to use 64-bit or even 128-bit alignment, for +-16 GB and +-32 GB respectively.
A library that can do that in Rust would be great.