@walsh (17 days later) I've played some matches with Spyglass. I'm ... pretty medium on it. Turn one Spyglass on the play hasn't been the backbreaker I was worried it might be, it's almost always been worse than a Sphere or Chalice for me. However, with a limited number of Spheres and Chalices available, it's not like you have to cut them to fit a few Spyglass maindeck. I've liked the card more than I expected in the mirror and against Eldrazi decks (name Eldrazi Displacer most often). The extra boost the card gives in the Drege matchup is notable, too.
My personal conclusion? I like the idea of running 1 or 2 maindeck ... but I wouldn't run 4, and I wouldn't value it too highly as far as mulligans and turn 1 sequencing is concerned.
Umori, the Collector in Workshops
Since most Workshop decks are all artifacts and lands you can play Umori, the Collector in your sideboard as your Companion. I know there isn't very many colored mana sources to cast it but it only takes up one side board slot and I think it would be OK to but in two Urborg, Tomb of Yawgmoth to help pay for it's cost. Also by adding Urborg in, your Ancient Tombs can produce mana without having to cost life and Mishra's Workshop can produce mana that can be used for other purposes than casting artifact spells, also good for Dismember.
@daniel-worobec umori conflicts with dismember. it also conflicts with boarding in leyline, but i think that's about it.
According to the link here: https://magic.wizards.com/en/articles/archive/feature/ikoria-lair-behemoths-mechanics-2020-04-02
"Your companion's deckbuilding rule applies only to your starting deck, which is the deck you begin play with each game. It won't consider any cards in your sideboard, so those cards don't have to follow the deck-building rule."
So you can put whatever you want in your sideboard and not have it the Companion requirements limit your sideboard.
@daniel-worobec yes, but if you board in any of those cards this will not function as a companion in those games.
On game one before you sideboard it is useful and useful if you still have all artifacts in game 2 and 3.
Not to mention the fact that it is just not a good creature for Shops decks...
Umori is always in your hand as kind of a free creature that is always available to cast. Aggro Shops always could use another creature with a decent power / Toughness that can also reduce the cost to play artifacts, very useful when you are trying to overcome Sphere taxing effects. It just takes the room of one sideboard slot.
I think the main issue is that this dude might as well cost 10 to cast within the context of your shops deck, and to use a spot in the 75 on it is probably irresponsible. If it had a tax effect instead of a reducing effect I would be more inclined to give it a chance.