Oberlander’s customs are very much not like Chasidim and they are more similar to Yekke minhagim than to Polish.
True Oberlanders for example wear a tallis starting at bar mitzvah, rather than waiting until marriage. They also often wear a tallis rather than a kittel under the chuppah and their tefilin are the same as Yekkish tefilin (square knot on head but the arm wraps like Ashkenazim not Chasidim) They do differ from Yekkes in that they are less into piyutim and many most wait longer than 3 hours (5-6) Also, much like Yekkes only say Av Harachamin on the Shabbos before Shavuos and before Tisha B’Av, the older Oberlander minhag was to say it on the Shabbos before Shavuos and during the three weeks.