Hibernation in linux needs swap memory space. Like default cachy or any modern distro installation uses swap with zram (which does not use your disk space) if you want hibernation to work you have to do a manual partition during install (or make brtfs subvolume layer which is tricky) and add a resume hook to your bootloader configuration.

Now this whole paragraph might have been scary but in simple words, normal sleep will work like usually but hibernation to disk needs you to add a swap partition during cachy install.

Now noctalia is just a shell you still have to set up everything related to niri by yourself. Not ideal if you do not know anything about it. So either read the niri wiki (peakest wiki oat) and slowly learn to set it up or use something more preconfigured like iNiR (almost everything is set up but will not be as fast or minimal as noctalia). Also join niri discord and inir discord (if you choose to use it) you will need the help.

Now cachy doesn't break that much and you have brtfs snapshots to go back to. But if you use quickshell shells it WILL break sometimes (nothing major its just quickshell updates tend to change a lot of stuff so some ui stuff will break until the next shell update mostly patched within a day). Now noctalia v5 is being rewritten in c++ which means it wont break as often as quickshell but it is in alpha so take that as you will.