The C64U comes with a function to online search and install software labeled as 'CommoServe'. This is actually a subset of a larger databae known as 'Assembly64'.
The following is about getting access to this large database on the C64U and is quite technical. This also something that was not the intention of Commodore that people would do it. If it works now it can that will not work anymore later.
Service to change the look of the default BASIC startup screen.
This is a replacement for the original C64 system font. You can use it with VICE or in a real C64 with a character eprom. 6 pixel uppercase height, better readability, mostly closed inverted text, consistent x-hight.