I don't need any particular technique for your Bitcoin holders just store it in a hardware wallet and it's safe and no one will reach it individually, no need to worry about tracking the flow of funds because we haven't committed a crime so what is there to be afraid of?
You are absolutely right in stating that investing in Bitcoin is not inherently illegal. However, it is unfortunate that in some parts of the world, investing/trading in crypto currencies is considered illegal, which is seen as unfair fair and against the interest of general public. In this situation, safeguarding privacy of investment is crucial to avoid any unforeseen circumstances.
It is essential for all of us to persistently raise our voices on all available platforms to advocate the regulation of Bitcoin. This concentrated effort can build pressure on legislators to address this long standing issue that affects many.
In some countries, bitcoin is still isolated because the government cannot control everyone who invests in bitcoin, so the counter government will oppose any form of investment that cannot control it, so it's no wonder there are still hiding people investing in bitcoin because they don't want it to be known by anyone including the government, so I think for now there are still pros and cons to this increasingly popular bitcoin.
I think there have been many voices of opinion about bitcoin, including in other forums, but the government's decision is still in their hands, but I am now quite happy that investing in bitcoin is not illegal and legal in several countries, it's just that transaction tools can't be used and fiat is their solution and that's what the government wants, bitcoin is still 14 years old I think it's still early for various countries to adopt it faster but wait in a few more years a revolution will definitely happen.