Hardened_malloc is a security enhanced memory allocator forked from OpenBSD and maintained and used in GrapheneOS. It protects against various memory exploits and works just fine on Linux, I tried Gaming and more.
The Fedora variant “Secureblue” has it preinstalled, they maintain the COPR and handle the preloading also for Flatpak apps.
By default Firefox doesnt accept that though, and gives some memory errors. Fedora Firefox should now work with hardened_malloc, as they applied a build argument to allow it.