Here: https://www.forth.com/product/swiftforth/ you can see that there is an object oriented version of forth available. Is there a free implementation with SWOOP support? I'm not afraid to build from source if need be.
You can find a portable version of SWOOP hosted on the Forth Library Action Group. It includes harnesses for VFX Forth and for SwiftForth, and - compared to the ASWOOP that comes with SwiftForth - most significantly lacks the [OBJECTS ... OBJECTS] local variable syntax.
I have harnesses that allow SWOOP to run on gforth and iforth as well. You can find a version of the gforth harness here. These are fairly easy to make though, unless your Forth is very unusual.