Yes, you can stream with this.
Yes, you can stream with this.
Yes, you can stream with that setup. The Ryzen 3 2300X and 8GB RAM paired with an RX 570 should handle most streaming tasks smoothly.
You have options for 720p/30 or 1080p/30 streaming. I think it's best to build it yourself. Download OBS, give it clear instructions and it will set everything up. For more demanding work like VTubing, this setup isn't ideal, though it's my final thought. If you can, consider switching to NVIDIA for better performance with minimal loss in gaming while streaming.