How to make gasless(EVM balance) transaction in Frontier EVM for certain Ethereum smart contract functions?

Question

How is gasPrice determined in Frontier EVM?

I found the following settings in the Frontier/template/src/runtime/lib.rs

impl pallet_evm::Config for Runtime {
    type FeeCalculator = BaseFee;
    type GasWeightMapping = FixedGasWeightMapping;
    type BlockHashMapping = pallet_ethereum::EthereumBlockHashMapping<Self>;
    type CallOrigin = EnsureAddressTruncated;
    type WithdrawOrigin = EnsureAddressTruncated;
    type AddressMapping = HashedAddressMapping<BlakeTwo256>;
    type Currency = Balances;
    type Event = Event;
    type PrecompilesType = FrontierPrecompiles<Self>;
    type PrecompilesValue = PrecompilesValue;
    type ChainId = EVMChainId;
    type BlockGasLimit = BlockGasLimit;
    type Runner = pallet_evm::runner::stack::Runner<Self>;
    type OnChargeTransaction = ();
    type FindAuthor = FindAuthorTruncated<Aura>;
}

impl pallet_base_fee::Config for Runtime {
    type Event = Event;
    type Threshold = BaseFeeThreshold;
    type DefaultBaseFeePerGas = DefaultBaseFeePerGas;
    type DefaultElasticity = DefaultElasticity;
}

Can I modifiy fn weight_to_gas(weight: Weight) to always return zero?

How can I set it up so there is no charge when certain accounts make certain Ethereum contract transactions?

Answer 1

Option 1: Make precompiles for all the EVM functions that need to be gasless. When Ethereum users call those precompile functions, they will see 0 ETH gas cost on their MetaMask.

Also, Moombean has a lot of precompiles written already like ERC20, staking, etc...

Option 2: Checkout ERC20-Permit developed by OpenZeppelin and Solmate for gasless token transfer