So, I was thinking that we could find a sysmodule(preferably one that loads at boot) that hasn't been updated at all since 3.0.0, and then create a homebrew application that modifies said module to allow homebrew to load on later firmwares. Once the module is modified, update the Switch to the latest firmware, and the modified module won't be updated, as there isn't an update for it. Kinda like ColdBoot Haxchi for the Wii U, where it loads the CFW when the console boots. If that module does get an update, modify a different module that doesn't get updated.
Basically, start with 3.0.0, mod sysmodule that won't get updated, update. Once you update (4.1.0, for example), and another update releases, and the sysmodule will be updated, find a different module that doesn't change from 4.1.0 to whatever comes next. Once you're off 3.0.0, it can be any sysmodule that doesn't change starting from whatever firmware you are currently on.
Kinda new to this (as in no homebrew creation experience, and I don't even have a switch,) but if this helps people who want to play Odyssey also use homebrew, then awesome!
Basically, start with 3.0.0, mod sysmodule that won't get updated, update. Once you update (4.1.0, for example), and another update releases, and the sysmodule will be updated, find a different module that doesn't change from 4.1.0 to whatever comes next. Once you're off 3.0.0, it can be any sysmodule that doesn't change starting from whatever firmware you are currently on.
Kinda new to this (as in no homebrew creation experience, and I don't even have a switch,) but if this helps people who want to play Odyssey also use homebrew, then awesome!