Yes, Spellcom is well worth it for plundering ideas. The enchanting and concert casting (multiple casters working together) rules are very interesting. There are a couple dozen example magic items, made with the Spellcom enchantment rules, which are recognizable for their D&D origins. As you have seen from the Wraith Recon book, the Grimoires have cantrips and spells. The cantrips are common magic and the spells are sorcery, but they use both use the Grimoire skill for casting.
I would also recommend Age of Treason. It also has a different enchanting system, has alchemy, and constructs. The author uses the core rules with modifications and some interesting blending of the magic rules. The cults of Glorantha don't exist in the same way. The main empire's religion is a pantheon of gods, has a mix of sorcery and divine magic, plus gifts (permanent) and blessings (one use). Cults do exist, but they may require the aspirant already have a pact with the entity or object of worship. There are interesting ideas for other types of organizations that may provide magic. Some people may have grimoire skills, but not know Manipulation. The grimoire may come from family, cult, club or some other organization. Spirit magic works somewhat differently in the world of AoT and I prefer this to the core spirit rules.
For that matter, most of the setting books tweak the magic to some degree and may offer some interesting alternatives. They could possibly local or regional magical traditions that the PCs encounter in their wonderings.
Vikings doesn't use common, sorcery or divine magic from the core rules. Spirit magic is modified for the setting. It presents rune carving, seidr, spa (prophesy), and shape-shifting forms of magic.
Clockwork & Chivalry uses alchemy to do essentially common magic and summoning. (I haven't read through this completely yet, and I know there is more to it than that.)
I just bought Deus Vult, but haven't had a chance to read it yet. Skimming through it I see divine magic (miracles), sorcery and spirit magic seem to be represented.