Hello, I am still trying to understand the risks of using a safety deposit box in Germany or UK. I asked a German company offering deposit boxes outside the banking sector about their confendiality and they replied:
"To open a safe box we will need your passport in advance to write the contract..
The renting is minimum 1 year, nobody will know it that you have rented a safe by us. You will get an invoice and you can pay in cash. We need no bank account and we have not to inform any institution."
Their price is 135 euro per year while in Switzerland is around 500.
The UK is also outside the EU but they need proof of address and payment to be done by my own debit or credit card.
The only issue with Switzerland is the very high price and costs to travel to there.
Don't touch Germany (EU) or UK (ex-EU). UK incorporated most EU law into UK national law before leaving EU so a lot of past EU laws still apply. With no proof of address options are limited I can see even in some developing countries. So maybe ask around wherever you are residing and try and get some sort of proof of address i.e rental contract etc.
You have a clear source of funds for the cash as you mentioned. So if in end cash is only solution it should not be an issue to maybe leave some with family members for example.
However do not go near crypto stablecoins if you don't understand them. USDT especially where addresses can and have been blacklisted by Tether at request of law enforcement.