Ok I feel this thread is spiraling a bit.
Two things:
- you dont need to downgrade to mod
- you cant downgrade without mod anyway
This is absolutely correct, using CFW (custom firmware) requires an exploitable switch which is achieved through hardware not software (pegascape excluded but that's only useful on specific models on certain low firmware versions). CFW is required to run homebrew or mods on your switch. Early models of the switch manufactured before roughly May 2018 also referred to as "V1" have an unpatchable exploit and therefore are the easiest to boot into CFW. Models after that release are known as "V2" and are patched requiring a soldered modchip to get CFW. The switch Lites and OLED models fall under the modchip requirement.
Is your switch an older model? You can check if it's patched using this site
https://ismyswitchpatched.com/
Yeah its more about if your switch "Model" is hackable - firmware doesn't matter its not the same rules as the PS4 exploit.
As explained this is also correct. As far as downgrading, it is completely possible to use CFW and a tool called "Daybreak" to install any firmware version you want to your switch, but it's usually never done except for research as CFW is updated to support the latest firmwares fairly quickly and downgrading offers no real benefit. Unlike playstation where jailbreaking is done via software exploits, switch is exploited using hardware so firmware version means nothing (again, pegascape excluded if you have a pegascape compatible switch you'd likely know).
Now let's quickly talk about fuses. Essentially your switch has efuses that burn when you run firmware updates preventing the system from booting if your installed firmware is too low and doesn't match the burnt fuse count.
Nintendo official bootloader checks fuse counts, boot with hekate/fusee = fuses don't matter
This is correct as using Hekate doesn't burn or care about fuses. Hekate is a payload that is used essentially as a launcher for CFW and choosing sysNAND or emuNAND or running Linux/android etc, it's also a tool for partitioning the SD card and accessing it via USB, it has a lot of functions and if you don't know what sysNAND and emuNAND are I highly suggest you do a little more research and explore the quick start guides here on GBAtemp
some people not able to boot when they downgrade too many firmware.
I've read about this from a few reports but I have personally ran FW 1.0.0 on my switch emuNAND without issue so I can't confirm this, my stock FW is 3.0.1 so it's not a drastic downgrade. That said mileage may vary so keep that in mind if you do downgrade.
Anyways I hope this post helped in clearing up some of the comments and replies here as it was kinda confusing. I only hope I could spread a little knowledge and education. If you are new or just want to learn more of the basics I suggest checking out the noob thread for switch hacking. Good luck out there!
https://gbatemp.net/threads/switch-noob-paradise-ask-questions-here.488277/
Also side note and quick edit. I may be wrong here but personally I've never seen a firmware update as an NSP, it's typically a folder of multiple .nca files. I would double check and verify your source before installing anything