PAN-EU, Austria, OSS

I run a new estonian business, doing PAN-EU, with all VAT registrations and also Estonian VAT Registration.

I’ve had anotification that I need to register for VAT or OSS for Austria. I guess I’ve just hit the 10000 EUR - EU wide threshold. I don’t have OSS set up, do I need to register for it? I have little interest selling to Austrian customers, and reckon it will be more hassle than it’s worth. Can i stop Austrian sales? I’m wondering what the best option is.