Slimefoot and Squees second ability, costing and requiring the sacrifice of a saproling, allows you to reanimate it plus one other creature
My guess is that Amulet of Safekeeping is R&Ds attempt to try and answer the question of how to ensure that Modern players can sideboard against multiple strategies at once so that your progression though a large Modern tournament is less matchup dependent
Note that you do not target their creature, they choose it, so it plays like a Diabolic Edict effect where they send in their worst creature, rather than a better creature
1 Miraidon: Scarlet & Violet Promos (PC-Exclusive Promo) $73.30 Looking Ahead The Pokemon Center Exclusive Miraidon promo takes its place on the throne as the most expensive Miraidon card in the Pokemon TCG, soaring well above its closest competition, leaving no doubt that this card is the most vibrant depiction of Miraidon in the TCG thus far
With this in mind, it seems unlikely that Glorious End will show up in the main deck, but it could be a sideboard option for specific matchups (it's a hilariously effective way to win the mirror)