RISCOSbits have relaunched their scheme to allow you to update your Pi 4 system to one of their systems (Pi Harder, PiRO Noir, FOURtress and PiAno machines).

The RISCOSbits systems add a lot of nice features ontop of a standard Pi (cool cases, SSD drives, more software, etc). If you already have the standard Pi, they will use that as the basis of a new system for you!
 
More details are on their website