How do you create the Multisig?
Each signer has to vote yes before the smart contract executes the staged transaction.
If you use software by a 3rd party, we are back to squear one.
The keys have 3rd-party software, but all they do is sign. Don't have a quorum from the same manufacturer. If it takes 3 signatures of 5, don't use 3 from the same company.
If you use Electrum, you are hoping that Electrum is not buggy or malicious.
From the string of your comments throughout this conversation, you seem to be making some weird, "I can't do it, so nobody can do it," false equivalency.
I don't know you from anybody, but I'm reasonably confident you're not more intelligent than all the highly incentivized people who have been, on the one hand, solving these problems against adversaries on the other hand who are every bit as incentivized to unsolve them.
None of the points I've made have been in any way groundbreaking or insightful. They're basic "I spent my free time for a year going down the bitcoin rabbit hole" stuff. You're throwing out incredibly basic objections as though they somehow mean the whole system is an unreliable fraud, but all it's really showing is that you haven't done even a cursory overview of the topic.
I'm really not trying to be rude here. People can understand code, even lots of it. People do understand it. They even understand the high-level cryptography these systems are built on. You might not, but that doesn't mean nobody does, much less that nobody can.
The aspect of security I talked about is reducing counterparty risk. What one can do to reduce counterparty risk is to have multiple systems, make them as independent as possible, and compare the output they create.
Example:
1: An air gapped Dell laptop with Electrum on Linux
2: Another air gapped laptop. From Lenovo with Specter on Windows.
Create your seed phrase offline with dice and put them into both.
Every address you create, every transaction you sign - do it on both systems and compare the output.
Now, both systems would have to be faulty/malicious in the same way to harm you.
Do these types of smart contracts exist on Bitcoin?
I am worried that in 5 years we will learn that some hardware wallets used side channels to transfer bits of your private key out to make it easier to guess for someone who worked at the manufacturer.
Just because you haven't taken the time to learn how this stuff works doesn't mean there aren't thousands of incredibly intelligent people who have been working on it for a decade and have actually solved the low-level concerns you have.
Example: If you use a single hardware wallet to sign your transactions, you have no way to know if the wallet transmits data out via the hashkey:
Search BTC multisig and you can learn all about it.
But nobody is creating them with pencil and paper.