The lazy structural answer is to stop being the seller. A merchant of record sells to the customer, handles VAT and sales tax registration, issues the compliant invoice with the right numbers on it, and pays you out. Paddle and Lemon Squeezy are the usual two for small software, and the headline rate is meaningfully higher than a bare card processor - roughly in the five percent plus a fixed fee range, but verify current pricing because both have changed it, and one of them has been through an acquisition since.
So the real trade is a few extra points of revenue against never having to think about this again. At $290 a year with a handful of EU customers the extra fee is small money and the mental overhead saving is not.
At higher volume it flips and people move back to processing themselves plus a tax automation add-on.