As of Scarlet and Violet, there are 9 unused type combos. These are:
Bug/Normal
Ice/Poison
Rock/Ghost
Ground/Fairy
Normal/Steel
Normal/Ice
Fire/Fairy
Bug/Dragon
Normal/Rock
In this post, I'll spitball ideas for a potential Bug/Normal type.
If anyone wants to draw it, then please, be my guest.
SnakeFlye
As the name suggests, this Pokemon is based on the Snakefly. Not the most original name, I know, but Pokemon has had some stinkers even recently (i'm looking at you Flamigo).
This Pokemon will have a long, slender, snakelike body, with wings all down the back of it. Big bug eyes, like Butterfree, with a stinger at the end, similar to Beedrill.
Any other features can be added as you wish, if you choose to draw it