You can set up and win most bets or chicken races with illusions.

Like throw an illusionary pile of feed off of the path of your opponents chicken, so it'll be distracted by it and let your chicken win.

Winning a bet can win you anything: from a free chicken dinner for your party, to getting into a party for free.

Illusory itching on others' private parts to get them super uncomfortable.

Illusory bugs on your face to make you more intimidating/disgusting.

Illusory smell to make people nauseous, aka targeted fart bombs.

Illusory screaming on only one ear

Illusory burning feeling on others' feet, aka DANCE DANCE MOTHERFUCKER - could be useful to apply to hands so enemies would be very likely to drop a weapon

Illusory "Aha, you stepped on glue! You can't move!"

Illusory feeling like you're underwater, feeling the weight of water in your movement and having to "swim" on air.

I wonder if illusion could make someone mix up the sense of limb placement - what I mean is, even if we have our eyes closed, we know where our limbs are in relation to the rest of our bodies, we can tell whether it's the right or left index finger close to our eyes. Fuck up that sense and the target will be helpless.

PF2e? Heighten it to Level 2 and cast Illusory Wall of Fire. It generates heat, sound, and light just like a real wall of fire! It just deals 0 damage. Your allies can move through it without giving up the game if their acting is good, and if you give a path through (no matter how lousy,) enemies are more inclined to go where you want them instead disbelieving by risking a pass through. Illusory Aqueous Orb is pretty for more localized area denial.

At lvl 1, Illusory wall of stone is a little less impressive but can be funny if you time it right. Delay until just before an archer or wizard's turn and box them off to force them to spend actions either moving or disbelieving.

Other fake persistent spells can potentially work out, though i think the real tech starts once you're lv 3 and get access to heightened illusory object & Illusory creature.

edit: Since the Remaster, Figment (ghost sound) gained the Subtle trait, meaning you can actually use it to lure things into ambushes without giving away that some gnome is shouting MINIMOSI TRAVISI and glowing around the corner. You can also use it to send coded messages to your entire party; Rats squeaking means danger, bats flapping wings means its clear to move up, etc.

I think it'd be very cool if they approached challenges like a hacker.

Instead of just tricking a target with a direct approach, use illusions to trick targets into helping them trick secondary targets.

Surveil a target to find out what a family member's voice sounds like in order to imitate it.

Use an illusory object to feign that you've taken something to bait someone into an over reaction that gets them in trouble.

That kind of manipulation.

Are you just listing the illusion spells you will have as you should have quite a bit more and its easy to get a few more than that as a gnome.

Prestidigitation

The most powerful illusory cantrip ever.