This sign in Hobo features a custom Easter egg umlaut. In German spelling, Ö/ö is equivalent to Oe/oe. The umlaut dots emerged from a small superscript e, which in kurrent handwriting looks like two parallel verticals. While umlauts with a superscript e and later two strokes or two dots were common for lowercase letters, it took much longer for capitals. Here, the e remained a separate letter – following the A, O, or U – for a long time. With the help of Google’s Ngram Viewer,Ralf Herrmann showed that the change happened around 1902, when spelling was standardized.
In some place names like Uelzen, the old habit of not putting profane dots on majestic capitals was preserved. In German-speaking Switzerland, it’s still the official rule, see Oerlikon. In the case of Oevelgönne/Övelgönne, the correct spelling is disputed. Maybe the unknown sign maker went for the fancy solution of an e nested inside the O’s counter to avoid the issue.