Just a few points

The ambulance crew would have requested police if you were a danger to others , if you did not have capacity , if you are volatile and multiple other reasons - or the police might have you put you under a sect 136 ?

If you had attempted suicide , you would be escorted to the toilet as until you had been seen by a clinician you would have been considered a risk to yourself

If the hospital discharged you into police custody, then they would have considered you not a high risk (you would have been sectioned and taken to a mental health unit )

I’m confused though from your post history - if your having mental health problems , taking various drugs are not helping