Shri Shankaracharya himself practiced devotion. Listen to what he says in his bhashya, in some of his commentaries. There are numerous verses in Sanskrit which clearly express his in-depth devotion to the personal aspect of God, in specific, Shri Krishna.
सत्यपि भेदापगमे नाथ तवाहं न मामकीनस्त्वम् । सामुद्रो हि तरङ्गः क्वचन समुद्रो न तारङ्गः ॥
Satyapi bhedāpagame nāth tavāham na māmakīnastvam. Sāmudro hi taraňgah kvachan samudro na taraňgah.
He says, “My Lord, although it is true that the individual soul is not different, is the same, is not different from the Supreme soul.”
That is another argument, a philosophical debate because the individual soul emanates from the Supreme soul. So he is non-different in many aspects; he is non-different from Him as well. So, although it is true that the individual soul is not different from the Supreme soul, and yet, “My Lord, there is a difference. And that difference is the same as that which is between the ocean and its waves.” The waves are born out of the ocean, but the ocean is not born of the waves.
In the same way, the individual soul is born of the Supreme soul, God, Brahma, but God is not born of the individual soul. God is the complete whole, as we discussed, and the individual soul is the part, the fraction, and this is how it will always be.
This is what he states in this verse.
