Lacking features

It's important to mention that the specific way by which 'immutability' and all of its associations are implemented, is key to determine what possible limitations are. Perhaps to gain a better grasp on this, consider reading this blog post. Note that due to the (very) active development 'immutable' distros enjoy, not everything found within that article is accurate.

and having to take weird extra steps to get what I want and tweak the system the way I want.

~~Does uninstalling snapd on Kubuntu fall under this?~~ Jokes aside, the way that 'immutable' distros want you to do stuff is simply unconventional compared to traditional distros. Heck, even the need to (soft-)reboot to apply changes to the base system is almost unheard of on traditional distros. However, unconventional does not necessarily imply weird. Care to elaborate when something goes from unconventional to weird?

I’m a bit of a power user and I’m wondering if a immutable distro could work for me over a regular one.

It depends on your priorities. There's a 'cost' that comes with going 'immutable'; mostly related to how it's still relatively immature and/or unpopular. However, even in this state, there are problems it solves and tackles that traditional distros don't.

Regarding 'being a power user', like what's even the wildest thing you'd want to do?

IMO it felt a lot like running Android.