The other article you mention comes from the same website: https://rxdb.info/offline-first.html. It's in an opinion section, giving the arguments from both sides.
I mean, read all these comments on both articles. People say offline first does not work, then they say that every software is offline first by default and it is nothing new.
It was totally worth it spending two 3 days on it :)
I feel like you missed the most important point of "offline first" is that your data belongs to you and does not need to be shared to the cloud in order to have tremendous value. The code/logic to enhance your data should be shipped to you, rather than the other way around.
Yes, I totally missed this side of the dice. Having your data stored locally, being in control, being able to reset the state to it's origin, export the local state as json and import it somewhere else, knowing what is stored and how long.