I recently discovered this gem of an interview conducted with Sri Nannagaru shortly before his Samadhi in December 2017. The interview is in English and is probably one of the last such interviews given by Sri Nannagaru.
If you haven't yet discovered the link vedicbooks.net at the left hand margin of this Arunachala Grace Blog, do please check it out. The organisation offers thousands of spiritual and newage books at discount prices. The categories include; Ayurveda, Yoga, Cooking, Jyotish, Healing, New Age, Best Sellers and Sale Books. The subjects vary from organic farming and history to Vedic mathematics and environment. As well as offering the books at discount prices, the organisation use book proceeds to fund many of their excellent programmes; which you can read about at their website.