Could you elaborate on the clear disadvantages of Shamir's Secret Sharing? The only downside I see is the complexity of the implementation, which leaves room for error and can decrease security if not implemented right. For this reason, we will also add other schemes like SeedXOR and Hamming Backups, which are much simpler and leave less room for error.
Yes I can, and I wrote more about it one of my topics called
Multisig VS Shamir Secret Sharing.
You can clearly see the pros and cons for both of them, and I provided links for reference, but I also listened to comments of some crypto security experts about this subject.
AirGap Vault does support multisig because it supports signing PSBTs. To do this, you'll have to use it with a watch-only wallet like Sparrow, Specter or BlueWallet. Please note that we didn't officially announce the support for multisig just yet, because we would like to add some additional functionality to make it more secure (eg. being able to register co-signers in the Vault to verify change addresses, which currently can't be done). This is on our roadmap and will hopefully come sometime in Q1.
OK good to hear, maybe you should write more about it when it's ready.
There is general lack of mobile wallets that support multisig, and I constantly see people are asking for this.
Can you post link or screenshot for AirGap roadmap?