Yoga at school: a spiritual practice?

In France and in many Western countries, Yoga has been introduced in schools and is experiencing a very significant growth, including in elementary school classes. This is what one discovers in the French press, which presents the practice of yoga as a means of relaxation in the face of students' anxiety, or as a learning aid to better control one's emotions and reactions. What does the practice of yoga at school mean? Is yoga compatible with Christianity? Is it dangerous for children? Is it a new form of religious teaching that doesn't say its name? Does secularizing yoga (for example, the posture of "greeting to the sun" changes to "greeting at work" so as not to include a star to be "worshipped"; children do not pronounce the mantra "aum"; but the vowels: the A, the I, the U, whose effect on them is similar) make it less spiritual? By changing the names of the spiritual exercises, could we really change their meaning and especially their effects? So many questions that the author, a practicing Christian, tries to answer through this book.