This might be of interest: https://verdagon.dev/blog/first-regions-prototype
It uses region-based static analysis without borrow checking: it doesn't impose aliasability-xor-mutability per object, or even per-region.
Though, if you'd like to move the goalposts further to no form of borrowing at all, then I recommend looking at languages like Forty2 and Verona, they might be what you're looking for.