Working out at home now with the pandemic, it'd sure be great to be able to filter on equipment.
I agree. Right now you can use https://connect.garmin.com/modern/gear
Click on the Activities link

Which will show a link to every activity using that gear.

That's pretty neat!
But I mean when browsing workouts at https://connect.garmin.com/modern/find-workout to add/send to my device. I want to filter out the workouts that need equipment I don't have. I don't have a squat rack.Or a cable machine.
I want to filter out the workouts that need equipment I don't have
Not currently a feature. Suggest sending your idea using the Share Ideas form - https://www.garmin.com/en-US/forms/ideas/