Saying "debian or arch" needs more explanation, since Debian and Arch are in some way opposites, but Hazel is right about switching being the only sane option.
If you prefer Debian, then consider
Devuan or
AntiX.
If you prefer Arch, then consider
Artix.
Otherwise, OpenRC is the default in
Alpine,
Gentoo, and
Hyperbola.
Devuan and Artix both support migrating from an existing install, but also both recommend installing fresh instead.
(Hazel: MX doesn't actually remove/block systemd, it only makes it not the default.)