I am a relatively experienced Aikido player but I've always struggled in the topic of openers. All I know is a noob clap (sometimes adding variations by using abs), a grab (single-handedly sometimes, sometimes rotating chest), a pretty bad kick, and that's pretty much it. If anybody could teach me some decent openers, I'd be very grateful.

Clapping is honestly the best opener you can know. It spreads out to so much it's astounding.

If you really want to learn more, though, just observe players. Public Aikido servers are great to find openers and variate them yourself.

As Hydra said. Akido is not about openers by any means. A simple relaxed clap with contracted wrists is enough to put yourself in a good position to move on from there. Sure. Some people get lucky with snapkick openers, but they are very easy to counter.
Akido
is
all
about
countering.

Speaking of countering, a good way to deal with snap-kicks is relax all. The whole point of countering and negating damage in Toribash is by making the person hit as many limbs simultaneously as possible. When someone concentrates all their power to one body-part, the most damage occurs. Other ways of "blocking" snap kicks include grabbing the leg (if possible), bringing the opposite knee up to the kicking leg, or getting as close to the opponent as you possibly can. The power increases as you get further down the leg.