No, the above assertion by @everythingfunctional is inaccurate.
The example I showed upthread with integer(int64_t) target and a pointer of integer(int8_t) of appropriate shape falls under the combination of Fortran type and type parameters case mentioned in section 18.3.1 Interoperability of intrinsic types in the standard.
It is the combination that I showed which makes it interoperable.
In a way this is similar to the situation with the Fortran standard whereby the C type of unsigned char is indeed interoperable with an integer type with a kind type parameter of C_SIGNED_CHAR.
It was years ago when Intel Fortran had fully implemented TS 29113:2012 as part of what was then called Fortran 2015 that I had first explored facilities in Fortran similar to the union type in C and challenged the standard to determine this was both viable and not excluded by the standard.