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.

• Jussi offered when making that post access to a proxy server free to use to make it work. There is also the information on github to setup your own proxy server
  • The information about the proxy server of Jussi ( as is)
    • To use it, put static IP on your C64U and for DNS address use 157.180.85.223 which is my server. That will spoof assembly64 address to point to my server and my server then alters request headers so you get REAL assembly64 files and not commoserve. To revert back, put your own DNS address instead.
  • Original FB-post about this with detailed instructions
• https://github.com/jusii/c64u_server_switcher - Offers the option to switch between CommoServe and Assembly64 from the GUI of the C64U

• FB-post from Dean W. about how he changed the default BASIC boot GUI
  • I wanted a more “modern” and colourful boot experience when I turn on my C64 Ultimate, so I'm using my custom “dark mode” kernal with an alternative font. Love seeing this when I turn it on, and it's nice to be using a fresh font. I might create some other designs too.
  • ⇒ https://c64.pro
    • Website where you can upload your own ROM file. The service will modify the file with the selected esthetic option. After payment of $3 you can download the file and activate it.
    • Works also with JiffyDOS and DolphinDOS

Example of the look after modification. More designs are available