IANAL but after working on GDPR topics for months with a lot of reading I'd say they would work. Selling data is still hard to argue, I'd not do that for EU ci

IANAL but after working on GDPR topics for months with a lot of reading I'd say they would work. Selling data is still hard to argue, I'd not do that for EU citizens ("tag EU citizens to opt out from selling data"). Everything else should be possible. Using Art 6/1(a) and Art. 7 GDPR you can store most of the data from your visitor. You need to make sure they can inform them about your usage, revoke their aggreement and make you delete it. Coupling ("click EULA or else") is a little bit more difficult, but with clever UI most visitors will accept the EULA instead of opting out, no coupling needed. I'm sure in 1y publishing systems will provide all of this out of the box.