Pyro right now is one of the best classes thanks to Agny Necklace. Thaumaturge definetly helps that cause agny is a multiplier, but thauma gives BASE MATK. it’s a nice combination.
Farming wise, thaumaturge can swell monsters, making them drop 2 times the items they should be dropping, which is cool i guess. It also gives you Swell Right and Left arm, granting you either a huge boost to your MATK/ATK or a decent boost of MATK/ATK + Phys Defense/Magic Defense, depending if as subweapon you have shield or dagger.
As for pyro2 linker1 chrono3 sage1, it would be more of a team build, maybe, but you could also get some nice combos like:
Double fireball + micro dimension + link + hangman’s knot on boss + (rest of combo = fire pillar flame ground) --> Pass (chrono3) -> repeat all but fire pillar.
As chrono3 you’d have most of pyro skills always up, which sounds pretty good, never played it myself so can’t say anything really. But in my mind it sounds fine.
Late game wise what you need right now is high MATK, and skills not dependant on link, which pyro with agny can give. Wiz1 Pyro2 Linker2 thaum2 sage1 is definetly good late game, the chrono3 i proposed is more theorycrafted cause i don’t think anyone uses it.