No worries. You have several places where you can store icons, themes, etc. The Book has some good information on this. You might not be running ArchLinux, but these paths will apply to you as well. You can basically overlap system-wide icons with user-specific icons in your home directory.

To easily get the icons from the system directory into your home directory you can just copy them and make the alterations in your home directory.

Also, like the others here also said: great work on getting so far in such a short amount of time!

The sudo makes this a bit suspicious to me. Maybe you can store the results in ~/.local/share/icons/hicolor (not sure if that’s exactly the correct path. It would allow you to run this for a specific user instead of doing things with your entire system.

What’s the use case? Is there a reason that the disk is not unlocked at boot/login?

I think any distro will do really. I’d go for something that is friendly to new users, if you’re not very familiar with Linux in general. For example: Linux Mint. Here is an example on how you can get your installation setup easily: https://www.youtube.com/watch?v=IyT4wfz5ZMg

Regarding your Valve Index. It will likely work, but don’t expect it to be very easy to get it running well. I’m currently on Arch Linux with red team hardware and a Valve Index. For example, you will need to ensure the udev rules are set properly: https://github.com/ValveSoftware/steam-devices. New issues occasionally arise, see: https://github.com/ValveSoftware/SteamVR-for-Linux/issues. Currently, it’s not switching audio devices automatically, so I use pavucontrol (with PipeWire) to switch that manually.