airgap-coin-lib VS tatum-kms

The audit reports have been released over 2 years ago (shortly after the audit report was done) and are available on github: https://github.com/airgap-it/airgap-coin-lib/tree/master/docs/audits

That being said, I can tell you a little bit about our experience. We developed our wallet to be blockchain agnostic from the start. All the coin specific logic is located in a shared library that is used in both the Wallet and Vault application (https://github.com/airgap-it/airgap-coin-lib/tree/master/packages/core/src/protocols). We have an interface for methods to prepare, sign and broadcast transactions, as well as generate addresses and fetching balances. To add a new coin, all you have to do is add a new class to the shared lib, implement all the logic and then add the new chain to the "supported protocols" in the apps. Everything else is handled automatically (besides coin specific features like staking, etc.)

AirGap was audited a bit more than a year ago by "Compass Security". The review is available on github: https://github.com/airgap-it/airgap-coin-lib/blob/master/docs/audits/report_85096_mobile_app_security_v1.0.pdf

do you know an equivalent of https://github.com/tatumio/tatum-kms for tezos? I'd like to have a solution to implement a custodial wallet for Tezos

Send, estimate, invoke, broadcast *Send XDC / ERC20 from account to account — sends XDC or ERC20 tokens from account to account using private keys. Tatum KMS can be used to ensure the highest degree of security. *Estimate XDC transaction fees — instantly estimates the current gas price of a given transaction. *Invoke Smart Contract method — this is how you interact with existing smart contracts on the XDC Network. Invokes any method according to several inputted parameters. *Broadcast signed XDC transaction — broadcast signed transactions using Tatum Middleware, Tatum client libraries, or a custom signing mechanism.