I had started the core idea of this deck based upon a unique rule in Primordial. Your sideboard is working under slightly different deck construction rules than normal Magic. Most “good” decks are abusing something, and this seemed like the perfect angle of attack.
To use this, I had to have a set with a Fae of Wishes // Granted card to abuse the sideboard. From those few sets it was a matter of what had either the most powerful thing to find or a variety of choices. Eldraine easily had both a variety of answers and one underdressed threat.
Those of us who have played with it are aware of the ridiculous power in Oko, Thief of Crowns. The idea is clear; just play with effectively two copies thanks to our wish and the walker himself.
Even for something like Oko you must develop a strong shell of a deck. The game plan is we just need to stall and infinite Elks can win any board. To that end food is both great at delaying our death and thanks to Trail of Crumbs it helps us find our Oko.
With both a way to delay and dig for Oko the only possible ways to lose would be non-permanent forms of interaction which leads us to our Didn’t Say Please. The remaining cards are either meant to be able to fend off elks in the form of Sporecap Spider or just recur Oko in the form of Once and Future.
The sideboard is mostly straight-forward once you know the idea behind certain cards and there are some clear matchup dependent things such as green’s self-hate card from Eldraine in Oakhame Adversary and our Return to Nature effects. The remainder are alternate wish targets in the event Oko isn’t our go-to and my personal favorite would be Midnight Clock to avoid being milled out. This sideboard could be changed to involve Mystical Dispute to combat combo decks especially since Frogify would be weak in a matchup such as that.
The strengths and weaknesses of this deck just reflect that of Oko himself. This deck can easily chew through anything playing to the board or fair in general. To beat this deck, you can play on a different axis such as a combo deck that doesn’t care about creatures. This weakness is emphasized by the deck taking a while to close and Eldraine lacks above average hard permission.