As of TrustVault x MetaMask version 10.2.24.2 and TrustVault iOS 2.7.1 released on 23rd March 2023 you can now send EIP1559 transactions.
As with the non TrustVault x MetaMask implementation, sending EIP1559 transaction is the default option. The MetaMask help documentation is very useful and worth reading on how the new fee structure works.
Changes to the TrustVault iOS app will also show when signing a transaction what the transaction type is. There are 3 options supported:
LEGACY - These are legacy transaction currently supported when creating the transaction via TrustVault Web or the Trust API. EIP1559 support is coming soon. This include the classic
gasPrice values which specify the
gasPrice you are willing to pay. The
gasPrice multiplied by gas used will be the total you pay for this transaction.
EIP1559 - These are the new transaction types which support the new
maxPriorityFeePerGas fields. The MetaMask documentation describes in good detail how these values work.
EIP2930 - These are specific transactions that allow access lists whilst following the old style legacy transaction
gasPrice values. MeteMask doesn't support these but this may be used for advanced API users in the future.