Is there anything you can forge like in America? I assume this is really important for you so I'd go for a drop-in private health practitioner, who isn't directly associated with your known name, so not your primary. Book an appointment under an alias and pay the appointment itself in cash, look clean behave friendly and casually, ask if they accept cash in payment for your time in advance, if you call do not call with your real phone number, use voip or otherwise. I'd bring close to 1k€ in cash with a little story prepared and a smile with some mildly humorous lines together that are prepared for use. I would tryfind an older private doctor who is also into alternative medicine/treatments, likely he will retire soon and won't give a shit. It might also be a bad idea to go to a top tier clinic with a lot of money, less likely they will need and be tempted by your money but you never really know. You might get rejected more than once and if this is important enough you keep trying, it will feel cringe but youll have funny stories to tell trust me.
If you get rejected by doctor and he declines your money you have covered your bases in the best possible manner(this may not always be possible but fuck it), anyways if you are declined leave and try again at another place.
Even better if you have access to any nurses of friends you can talk to directly they might again know someone etc.. After all its a free 1k for a really simple favor. The risk problem for the doctor is he will facilitate it for you and it's 1 extra mouth(nurse) because of 1 bitch he could lose that license, etc.
If there are nurses/anyone who can give you a shot without you making an appointment(imo it's a killshot likely tied to name) I'd go straight there stand in a line with a stack and an euphemism and show cash lined up when its your turn to sit down, that's probably the fastest and best way, maybe just 500 would do in that case but 1k is probably enough. If the nurse declines you get up abruptly and leave. Try again another place.