Sorry, but USB-A is not compatible as it only supports the USB protocol. Everything needs to be done over Thunderbolt protocols using an Apple USB-C to Thunderbolt 2 Adapter combined with an Apple Thunderbolt 2 to Firewire Adapter.
However, even this combination may not work since not all devices are compatible with an M1 Mac (assuming an M1 Mac since it is "new"). I've was assisting another user with connecting old Firewire drives to an M1 Mac, but the user was unsuccessful. I have personally had compatibility issues with even some USB-C devices and an M1 Mac, so it would not be surprising to see compatibility issues with even older hardware.
At least with old hard drives it should be possible to remove the physical bare drive from the Firewire enclosures to use a USB Adapter to connect them to the new Mac. There is still a risk of the USB Adapter not being compatible with an M1 Mac, but at least there should be more options. So far I have not had any compatibility issues with devices utilizing the ASMedia USB chipset, but not all vendors list the chipsets used with their products. Here is one option for a universal hard drive USB adapter which can handle both the old IDE interface common with many Firewire drives and even the newer SATA interface.
https://www.startech.com/en-us/hdd/usb3ssataide
