Has anyone tried using the Testnet to conceal their Bitcoin wallets? It seems to me that using the Testnet as an apparent primary Bitcoin wallet, and switching to a mainnet wallet for real transactions, would introduce a level of obfuscation that may fool some less sophisticated attackers or investigators. You could also maintain a variety of wallets on external drives to increase complexity.
Hmm, TBH for some of the free airdrops I've joined many testnet projects, and for testing purposes as well even some of the Bitcoin L2 tenets I've joined, in the last couple of weeks but the reason OP mentioned was not even in my imagination, because I'm not sure how many of the users will prefer to use a dummy wallet first to avoid these kind of attacks the outcome efficiency of this strategy is also unknown.
In my view if you hold a lot of the funds you should prefer using the hardware wallet and if you cant afford it, make sure to use the mutl=signature wallet, there some more alternatives as well but the best of all is Hardware wallet, and the multi-sign wallets. For more additional layers like 2fa and other different wallets that provide different ki nd of features set, make sure to find the open-source decentralized wallet.