I am in the same situation
Yes, you are eligible according to Article 5 of the Interrail’s official website:
5.2 The Customer is eligible to purchase an Interrail Rail Pass, if the Customer is a citizen or official legal resident of:
or
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one of the other European countries: Albania, Andorra, Belarus, Bosnia Herzegovina, Faroe Islands, Gibraltar, Iceland, Isle of Man, Kosovo, Liechtenstein, Moldova, Monaco, Montenegro, North Macedonia, Norway, Russia, San Marino, Serbia, Switzerland, Turkey, Ukraine, United Kingdom or Vatican City.
5.4 Citizenship can be proven by means of a valid passport or legal equivalent. Residency can be proven by means of official residence documents issued by the government. This must be a document that clearly proves that the Customer is registered in the country where they live. Such documents vary by country.
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Just bring your residency card, or documents proving your residency on board the train.
You will-if at all-ONLY encounter potential probs IN the country of nationality if you travel more as the usual 1 trip OUT and IN. It should be evident that large+expensive countries like DE and GB are quite keen to prevent their citizens in getting super cheap rideatwill tickets for travel in homeland.