Is the repentance of one who drank shampoo while unconscious due to taking psychiatric pills with severe side effects, such as suicidal ideation, accepted? And is their prayer accepted despite their feeling that God is angry with them?

If you consumed substances with the intention of suicide or knowing their harm and without medical consultation, you have erred and sinned. You must offer sincere repentance. If you repent, rejoice in Allah's pardon and forgiveness, for "the one who repents from sin is like one who has no sin." Have a good opinion of Allah, and increase your acts of obedience and good deeds, for "indeed good deeds efface evil deeds." Be confident that your acts of worship will be accepted, and that after repentance, you will become, by Allah's will, like one who has not sinned.