There are a few curious turns in Marriage of Sellers (D2d6 Mar. 25, 2021) 2021 WL 1134891, No. B306844 (unpublished). While unpublished, it provides a good roadmap – with citable authority – to making a limited appearance on behalf of an out-of-state litigant without waiving jurisdictional challenges.
And if one is inclined toward a cynical view about appellate courts' selective treatment of appealability issues as "jurisdictional," it furnishes some confirmation of that, too.