Psychic as mentioned is a go to for amped guidance or message. Alchemist is nice with minimial class feats for some alchemical items (but they're use is typically limited at the levels you get them).
However I'm going to suggest a silly combo for a recall knowledge master.
Step 1: take the familiar thesis (adds familiar abilities for skilled)
Step 2: take enhanced familiar at L2 (class feats) (more familiar abilities)
Step 3: MC into Cleric
Step 4: Grab two focus point spells for a god with the dreams domain and one with the knowledge domain.
Step 5: Grab the Lore Master archetype
The dreams domain initial domain spell can get you a hour long +1/+2/+3 status bonus to INT or CHA skills. Later we can supplement this with Pocket Library casts so we can spend more focus points on the knowledge domain spell.
The knowledge domain initial domain spell can give you advantage on a recall knowledge roll (basically a +1-+5 depending on the DC)
The familiar (once it has 4 abilities) can pick up skilled (occultism), Skilled (Arcana), Second Opinion (gives a +1 to +2 circumstance Bonus), and later Skilled (Religion) at L6 and Skilled (Nature) at L12 (or pick your lore master lore).
Then you can go further into cleric for spells so you can use a staff of healing for heal spells for varied support options.
You might consider a Ghoran (they have the skilled human heritage feat) and then use the L1/L9 feat for a floating Trained/Expert. If your GM will allow it an elf with the ancient heritage feat could also get loremaster at L2 along with the cleric dedication so this build is effectively done at L4 (the FA variant rule lets GM hand waive archetype exit feat restrictions). Since you plan on taking those feats at L4 and its all geared towards being a savant of recall knowledge I would think the GM should be okay with it. Otherwise you are 'done' at L6 instead.
Example With Ancient Elf and Exit Feat Hand Waive:
Class Feats
L1 - Cleric - Dedication (from Ancient Elf)
L1 - Wizard - Familiar (wizard thesis) (3 traits now)
L2 - Wizard - Enhanced Familiar (5 traits now so I'd pick arcana, occultism, and loremaster lore or religion if not allowed)
L4 - Cleric - Basic Dogma (Domain Initiate - Dreams Domain)
L6 - Cleric - Basic Dogma (Emblazon Armament for the L8 feat raise symbol)
L8 - Cleric - Advanced Dogma (Raise Symbol, ensure you take 'the general shield feat at L3 or L7 so you get +2 circumstance bonus to AC and all saves when you raise your emblazoned shield.
Free Archetype Feats:
L2 - Loremaster - Dedication (now you have loremaster lore)
L4 - Cleric - Basic Dogma (Syncretism, now you can pick another diety with the knowledge domain which also puts you at 3 focus points.
L6 - Cleric - Basic Spell Casting
L8 - Loremaster - Assured Knowledge (1/rnd free action recall knowledge with assurance only)
Ancestry Feats:
L1 - Ancestral Longevity
L5 - Ancestral Paragon (+2 circumstance bonus on any skill check as long as you take twice as long)
L9 - Expert Longevity (you can bump your loremaster lore to expert a full 6 levels early and switch it at L15 when you get legendary in arcana or occultism). Some GMs won't let this work on loremaster lore because its a 'special lore' which as far as I'm aware has no mechanical definition. But in practice you can't gain access to it from feats like 'additional lore' but most people let feats that effect lores to generally apply so you 'should be fine'(YMMV).
There are of course other high level options that are great (L12/L18 for more spells from cleric, or high level lore master feats).
Thaumaturges WISH they could be this good lol. Feel free to move stuff around based on what your GM will let work.
