I believe Rav Shlomo Wolbe ZT”L went to the early 20th century German equivalent of public school until he was old enough to go to Yeshiva.
L’Havdil, Rav Malkiel Kotler SHLIT”A went to Betzalel, a non-frum Jewish school in Lakewood.
Public schools back then did not teach the pritzus they do now. They were much worse. Most secular schools in the 20th century were very into Atheism and openly anti-Semitic. There was no accommodation for religious lifestyles and Jewish students were actively encouraged to discard their old fashioned dress and religion.