Which External PCIe enclosure for Mac mini 2014 Thunderbolt vs USB3 Configuration

I have a M.2 NVME NGFF SSD Enclosure, RTL9210B Chips, USB C 3.1 Gen 2 10Gbps NVME, 6Gbps SATA PCIe M-Key(B+M Key), External Solid State Drive Support UASP Trim for SSD Size 2242/2260/2280

installed in enclosure is a NVMe PCIe M.2 2280 Internal SSD High Performance Solid State Drive

Using on Mac mini Macmini7,1 Intel Core i7 3 GHz

Running Mojave mostly and Big Sur

QUESTION:

Which connection will give me the fastest read/write on that external SSD

Thunderbolt 2 (pretty sure that will require a power source)

is there a simple uncomplicated way to used my Enclosure/SSD on the Mac mini Thunderbolt 2 port

since the enclosure is not powered?

Or am I limited to USB 3?

I am getting around 420MBs Read/Write through the USB port

Hoping a Thunderbolt 2 will get me closer to 700MBs if this enclosure will work

will the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter still require me to power the external?

or will it plug and play through that Apple adapter?