You may not get any wallet that is multichain and having bitcoin multisig, but you can get multisig that has the features. You can go for Electrum or Sparrow wallet multisig.

I will advice you to deal with bitcoin separately from altcoins.

Well maybe we should start from permissionless, I don't  really know what you mean by the permissionless?? What kind of wallet were you using for your holding...

You said you don't  want a government or company to deny your access ,
If so then you are definitely  using a custodial wallet which needs permission  from third party to make your transaction (this is how I understand  you word "permissionless " correct me if I'm  wrong ")

If you need a multisig wallet then I only know of BTC-only wallet ( Electrum  and Sparrow) you could create multiple cosigner  probably two and you can make the two accessible  to you which means for every  transaction  make  you need to sign it in two places .
 
You need to understand  that Electrum and Sparrow are noncustodial  Btc-only wallet , which means you have full control over your wallet to the extent of determining  the kind of fee you want for your txn,
What do I mean by BTC-only wallet: you can not store any tokens along with your BTC

I think he is referring to custodial wallet. Wallets that you have your private key and the full control.

It is not opposed to m-of-n but in support. You will need your private key or seed phrase and the cosigner public keys to set up the wallet. The cosigners will need their own private key or seed phrase and your public key and other cosigner public key to set up their own wallet.

Example is 2-of-3 multisig. It means 3 public keys are needed to set up the wallet. Your private key will generate your own public key for you and you will need 2 the other two cosigners public keys as they will need yours two set up the wallet. The 2 there means 2 out of the 3 cosigners signature are needed for making transaction.

I guess I was right afterall....check  my quote

For this
Custodian => Custodial
You check the link to understand
https://www.coindesk.com/learn/custodial-wallets-vs-non-custodial-crypto-wallets/

Incase you later feel like settling  for  a noncustodial  wallet then you should understand  how the transaction  and fees works
Check
https://bt.irlbtc.com/view/5320216.msg56441031#msg56441031

If it is 2-of-3. Yes. Two people among you three can make transaction on the wallet.

To initiate a transaction? If the wallet has already been set up, the multisig wallet has the 3 (you, A, B) public keys already. But just need any 2 signatures among you for transaction.

I think we had some miscommunication. I use Ledger and Trezor wallets, which I believe you'd agree are permissionless/non-custodial. The problem is they're not multi-sig wallets, they're single-sig. I want 2 of my 3 hardware wallets to approve any transaction for any asset on any network.

Thank you

I want 2 of my 3 hardware wallets to approve any transaction for any asset on any network, including Bitcoin. Do you know of such a product?

For other assets I don't think you can do that in trezor only 4 thirdparty wallets are supported check the link below

- https://trezor.io/learn/a/third-party-apps-and-trezor

Exodus have multiple coins and token supported but it does not have multisig feature but Electrum it does but it only support Bitcoin.

For Electrum multisig guide trezor already have a video guide about this check the link below.

- https://trezor.io/learn/a/what-is-multisig

So you don't have any choice but to use multisig only for Bitcoin and use single key for other coins.

Thanks for the help, everyone!

To summarize: There are Bitcoin multi-sig wallets but they do not support any altcoins.

I will keep looking for a multi-chain multi-sig.