How to modify a compose key sequence?

[charmoniumQ]

I have kb_options=compose:ralt, so I can type right_alt + < + > and hyprland inserts a ⋄ (diamond operator).

I would rather have this same key combination insert a ◊ (lozenge), but keep the other compose key sequences?

In X11, you could modify ~/.XCompose. What's the hyprland equivalent?

[MHellmund]

In X11, you could modify ~/.XCompose. What's the hyprland equivalent?

The same. Wayland uses ~/.XCompose, when present.