@simone dell'aquila I see! Just to try, what happens if you change your region to Sweden just when you try to set it up? Settings → General → Language and region → Region → Sweden. It shouldn't make any difference, but it's worth a try. Also, try to generate a new eSIM QR-code on “Mitt3” and see if it makes any difference.
Do you get the same error message? Do you know if you iPhone may be locked to your Italian carrier?
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