Here is a route for S.txt created by the NSO modder Frostworth.

https://docs.google.com/spreadsheets/d/1mSYQsNqYBw_qSPg1bj5R3BDeA71-dFY90ZXXPVzkjQs/edit#gid=485732569

Here is also a TAS example (also from Frostworth)

Though this doesn't make use of tricks and glitches, such as skipping Darkness, nor Day 2 Exploit. So there may be room for improvement. This could at least serve as a base, if anyone is interested in making a better route, or if you just want to do a 1.1 S.txt speedrun (since there are none, as of when making this guide).