Went into a Banco Galicia branch in person in a provincial capital today, and was not able to even get started opening an account with CDI / passport.
I believe the guy would have helped me if he could, he was polite and kind, even apologetic, but according to him the problem is primarily with their systems, rather than a lack of will to do so... he said that before the pandemic, it had been possible for them to do so. So this clearly applies to online as well, since apparently the same system is ultimately used whether you apply online or in a branch.
This was in spite of my showing him the mandate given by the Banco Central, that states that "financieras" are obligated to open accounts for foreign clients and that there is not really any good reason under the law for them NOT to do so, if they can supply CDI and passport.