Drip watering 5m flower bed from downpipe

I have a 5m flowerbed at the front of my house that is under roof cover and so gets no direct rain onto it. Beside it is the downpipe from the roof guttering and I can’t help but wonder if I could just feed a single 5m tube/piping from that with tiny holes to drip water the flowers.

I have 2 questions;

1. Does something like this exist already? I’ve found this type of part which appears to direct water into a tank: https://www.tanks-direct.co.uk/black-rainwater-filter-collector-2000840.html?fee=3&fep=1565&gclid=EAIaIQobChMIraHxo9rc6gIVSLDtCh3NBgSmEAQYAiABEgLjI_D_BwE

I wonder if I could just attach a hose to that and pierce some tiny holes all along it?

2. If I did use something like the above, should I be worried about the volume of water coming down the downpipe and flooding the flower bed, and what happens when the hose fills up because there is more water entering it than is leaving via the tiny holes.

Thank you.