What are some examples of surnames written with 変体がな? Are there any common or famous surnames with 変体仮名?
Rather than surnames, 変体仮名 were frequently used in names (specially female names). Before 1948 there were a lot of women with 変体仮名 in their registered names. After that it seems that the law for naming a child changed and nowadays you can only use the registered かな and 漢字.
In this website you can take a look at a lot of registered 変体仮名 that were used before. https://www.benricho.org/kana/a.html
About a specific 変体仮名 in a name, they are difficult to find but here is an example.
From right to left: すぎ、みな、、すゝ（すず）