Which CPUs does the X13SRA-TF support?

It uses socket LGA1700 and supports Intel Xeon E-2400 series plus Core i9 processors. Check Supermicro's CPU support list before buying, since not every LGA1700 chip is validated.

Does it support ECC memory?

Yes. It takes DDR5 ECC DIMMs in its two slots, which is the main reason to pick it over a consumer board. Non-ECC modules may work but lose the error correction benefit.

Is there any M.2 storage support?

No. The board has no M.2 slots, so plan on SATA drives or a PCIe add-in card for NVMe. That matters for boot drives and fast storage.

Can I manage it remotely?

Yes. It has an onboard BMC with IPMI-style remote management, so you can power cycle, monitor sensors and access the console over the network without a monitor attached.

Is it good for gaming or a general desktop?

Not really. It lacks Wi-Fi, audio, display outputs and multiple-GPU support, and its two DIMM slots limit memory. It is built for server and workstation duty.