What would be the right Pinephone OS for me? (mainly from Ubuntu background dev)

[ryo]

I was expecting to be able to just do stuff like sudo apt install htop etc... but that did not happen.

At this time I still haven't figured out what is the equivalent thing of apt for KDE Plasma Mobile eg. is it yum/pacman/etc...

From what I understand is thet KDE Plasma Mobile that comes with the current batches of Pinephone is running on top of Manjaro.
So "pacman" is used on it.
If you absolutely can't live without "apt-get"/"apt"/"aptitude" (just why do Debian based distributions have 3 different package managers these days?), I suggest Mobian.
Even for other reasons I recommend Mobian, it's by far the most daily driver ready apart from UBPorts.
I actually use it as my daily driver even, and leave my iPhone, Android phones, and Ubuntu Touch phone at home (I take my garake with me for LINE or the 10.000 in 1 possibility of being called by someone).

I did see there is Ubports... I might try that. I'm coming from web development side I was intending to use VS Code for example and run Node locally but maybe I completely misunderstood what this phone can do right now? I think VS Code can run on ARM.

While UBPorts can run desktop software through virtualization (a kind of docker-like environment that doesn't even work most of the time), it's for all tends and purposes a typical mobile OS.
If you want to run VS Code, you'll be better off using Mobian instead.
Or otherwise learn how to use VIM or NeoVIM, since terminal apps work perfectly fine on UBPorts.

I also noticed the dock doesn't charge my phone. I'm still trying to get video output from the dock to an external hdmi monitor, was looking at some threads.

In my experience, the USB connector of the dock is just a bit too loose.
Make sure you put the phone in a fixed position and not make even a slight move of the dock, or it'll disconnect again.

I think I will have to get an SD card/try different OS's that way.

Have fun.

I'd appreciate any thoughts. At this time I'm more interested in the dock-computing aspect than an actual phone eg. sms.

See all the other mini responses I gave above, and responses from others here too of course.