Looking to maximize security for BTC holdings (input wanted)

I currently have my assets split on a Trezor 1 and a Ledger Nano S +, with ETH on Trezor and ADA on my Ledger as well. I have my seed phrases secured properly, but I'm finding that as my portfolio grows, I'm becoming more paranoid about the possibilities of losing these assets.

Wrench attacks- This is something that I've been growing more concerned with given how many data breaches I've seen over the years, such as Coinbase or with things like Celsius or Blockfi bankruptcies from 2022, etc. I've got things set up to where they would have 0 chance of actually getting a hold of my seed phrases and I've thought about either keeping decoy wallets OR just storing my cold wallets where they would never be immediately available. Another idea was setting up multi sig, I'm a bit on the fence about this though and not sure if it is necessary.

However, my main concern is if somehow my wallets themselves are compromised. The Ledger not being 100% open source partially concerns me, but I'm not sure if I'm being excessively paranoid about this. My intent with my BTC is to buy and hold for the long term, so I want to feel it is safe to just park these assets on a wallet.

I've thought about possibly getting a BTC only wallet and consolidating my BTC holdings into that specific wallet, while leaving my ADA and ETH on the others that I currently have them on. I know that apps for other alts can potentially lead to another vector that can ultimately compromise my BTC, but again I'm not sure if I'm being overly paranoid about this.