You can find some examples here (in French - smartphones): https://www.indicereparabilite.fr/appareils/smartphone/

The score seems to be a weighted average of various scores, such as:

- how easy is it to disassemble the machine

- any specific tools needed

- what type of attachments are used to hold things together

- for how long is the documentation accessible

- how long are the spare parts available to be bought - how fast is the parts delivery

- how does the parts prices compare with the overall machine price

- information on the updates

- how easy it is to do a full software reinstall

- free remote support

etc...

Self assessment = garbage information.