score:2
I paid for the Fit for Flight tests and got the certificates for the way to Italy and my return to the UK. But Ryanair didn't once check these on the way out because they were in a rush and on the way back they just wanted proof of a negative test, which I showed them the fit for flight certificate.
The border force for both Italy and the UK have all your records stored digitally through the PLF. This is probably where they can view the Fit for Flight certificates.
Ultimately I think Fit for Flight tests are needed as it's checked automatically by border forces but it's still a waste of money as it's the same LFT that you take with the NHS (for me the exact same branded box). The only difference is you don't submit the result to the NHS, but rather their own system and they send you a PDF/certificate after.