Are you sure?
Almost all manufacturers specify much better than +-5nm.
for example:
Thorlabs designs and manufactures components, instruments, and systems for the photonics industry. We provide a portfolio of over 22,000 stocked items, complimented by endless custom solutions enabled by vertical integration. Thorlabs is comprised of 22 wholly owned design and manufacturing...
www.thorlabs.com
Thorlabs also specifes <0,5nm for a 350-700nm range which is exactly what a hobbyist would need.
The LR1 is very old and already uses a 3600px wide sensor. (which isn't even in production anymore)
The newer LR2 version is advertised with a much better resolution.
Might be that the "usual 1024" sensors you talk about are long gone history.
The 3600px Toshiba sensor is older than 26 years by now.