How does the thrower automatically spit items?

I'm using the MC version 1.16.4 and would like a command block to be triggered when a redstone signal is triggered. He should then throw a minecart onto the tracks. So far I had it with "/ data merge block -135 25 -258 {Items: [{Slot: 0b, id:" minecraft: minecart ", Count: 1b, tag: {Potion:" minecraft: dispenser "}}]} "tried, but unfortunately failed. Does anyone have any ideas?

It could work with a debug stick

/ give @s debug_stick

Unfortunately did not work. I hit the command block and launcher with the debug stick (left click)

OK, too bad