Going through my usual scanning of all the "-next" Git subsystem branches of new code set to be introduced for the next Linux kernel merge window, a very notable addition was just queued up... Linux 6.10 is set to merge the NTSYNC driver for emulating the Microsoft Windows NT synchronization primitives within the kernel for allowing better performance with Valve's Steam Play (Proton) and Wine of Windows games and other apps on Linux.
Is this an alternative to FSYNC and ESYNC?
Yes.