Who is the Imam who, due to the intensity of his devotion in prayer, did not notice a snake that fell on him during his prayer, and can devotion in prayer reach this extent, and if it is true, how can we achieve it?

There is no knowledge of an Imam upon whom a snake fell while he was praying. Devotion (khushu') in prayer can transcend such occurrences, just as it happened with Abdullah ibn Al-Zubair, Urwah ibn Al-Zubair, and Abbad ibn Bishr, who would forget everything around them due to their delight in communing with Allah during prayer.