Is the Lexar NQ780 good for gaming?

Yes for storing and loading games. It is a Gen4 NVMe drive, so load times are fast. It is not the fastest drive for moving huge game files, since it lacks a DRAM cache.

Does it fit a laptop?

It uses the M.2 2280 form factor, the most common size. Check that your laptop has a free M.2 slot that supports PCIe Gen4 or is backward compatible with Gen3.

Does it need a heatsink?

It is a bare M.2 drive. A heatsink helps under sustained load, and many motherboards include one. Light everyday use does not require it.

Is it faster than a SATA SSD?

Yes. PCIe Gen4 NVMe is far faster than SATA in both sequential and random access, so boot times and app launches improve noticeably.

The drive itself. Mounting screws usually come with your motherboard or laptop, not the SSD, so check before installing.

Is it worth it over a premium Gen4 drive?

For everyday use, yes. Premium drives are faster in sustained writes and heavy workloads, but most users will not notice the difference in normal tasks.