Try the new hide options to hide product option select boxes
Under a bundle condition, you can use the new hide options to hide the product option select boxes. When the boxes are hidden, only the 1st variant can be added to the bundle. Other variants cannot be added.
Let me know if you want to hide other stuff like a particular product option, option values, or variants, and I'll try to fit them into the pipeline!
Here's a quick demo video: