First house rule from my P2e remaster game, offered for your review.
Spell Slot Heresy
Since Pathfinder is balanced at a per encounter level, per-day limits on daily abilities are largely only kept around due to tradition. And tradition is just peer pressure from strangers, I don't see a good reason to follow it.
Any spellcaster can recover spent spell-slots with a one-hour activity, as noted below, while characters with focus points can recover them during combat.
Recover Magic
Traits: concentrate, exploration, manipulate
Requirements: You have expended a spell slot or used some other once-per-day activity
You spend one hour to recover your expended magical power.
During such time you may not work on any other activities or actions or be treated for wounds. At the end of the hour you regain spell slots or once-per-day abilities as per your daily preparations. If you have cast spells from a wand or staff, the item also regains any expended uses or charges.
If you are a prepared spellcaster such as a cleric or wizard, you may not replace what spells you have prepared for the day.
Refocus (1A)
Traits: concentrate, flourish, manipulate
Requirements: You are missing at least one focus point.
You take a moment to perform some deed to restore your magical connection, such as touching a talisman, speaking a phrase, or simply taking a breath. Doing so restores 1 Focus Point at the end of your turn.
EDIT: For the record, please presume the above is all released under the ORC license as a derivative of Player Core 1.
Thanks for the examples and feedback!
Yes, this is a very slight increase to character power, which is why its called "Spell Slot Heresy." But since this is for a TTRPG and not a video game, any GM who lets this "remove all challenge" would probably pull the punches and let the PCs win anytime. Consider:
Fire Ray and Moonbeam are both 2A spells that do ~1d6 per level fire damage plus a little extra. At best they're removing one target per round, and the monster core is full of creatures with "Immunitiy: Fire". Not to mention both become 3A activities if they want to recover their focus point, meaning that cleric or druid doesn't have a third action to sustain, move, raise a shield, or take cover.
Ki Strike is a status bonus to attack, which doesn't stack with either Courageous Anthem or Bless. Meaning the net effect is that, for three actions, the monk can attack twice with +1d6 damage. Strong for a third action, maybe, but half that power comes from a core monk ability that is by itself only about on par with a fighter taking 2 attacks.
Hand of the Apprentice is honestly on par or behind damaging cantrips like Divine Lance or Ignite. "Spend 3 actions to make one melee strike at range" isn't all that unbalanced, esp since that same wizard could have wands and scrolls of fireball.
While resource-management for the adventuring day SOUNDS like it's worthwhile, the most common pattern in literally every game I've been a player for in any system is for the GM to say "you get all your stuff back". Even in pathfinder there's no real guard against the party deciding "we rest until we're healed." Pazio knew what they were doing when they designed P2E, and it wouldn't be as good as it was if they had made resource management a real part of the combat-game balance. Since what matters is just the relative scale of PC power and the round-to-round action economy, simplifying or removing resource management is something that Pathfinder is very well adapted to.
If you and your players (or GM) really want a resource management minigame, I'd suggest house-ruling in the opposite direction and make HP and spell slot recovery harder than they are in Pathfinder 2e. But that's an entirely separate discussion.