Tips for brushing teeth when toddler refuses/fights (14m)

It seems like every time is a fight. She will mostly just refuse to open her mouth, push the toothbrush out with her tongue, or bite down so hard that the brush can't move.

We have a double sided toothbrush, I read it helps brush top and bottom at the same time but we don't really do that anymore.

I've tried the method of laying her down and putting my legs over her arms. She just clamps down on the brush. I've also tried hooking my finger to pry open her gums in the back but she thrashes her head and makes gagging sounds (pretty sure she's not actually gagging) and I can't get any brushing done. I have a silicone dino toy that's meant to hold their mouths open, but same results as the finger.

Any tips??? I'm getting angry and losing my shit daily.

(She has front teeth top and bottom, and 1 molar coming in)