People can be forgiven for making mistakes, especially on Ichigo's power levels, as they require a lot of scaling, but, assuming Mugetsu is a 2x multiplier from Dangai Ichigo, then TYBW hollowfied bankai ichigo is about 20,000x planetary level.
My reasoning is as follows: The hollowfication multiplier is a 1000x multiplier as it was on par with SE Ulquiorra, who was 1000x stronger than Ichigo's first bankai. To clarify, I am talking about the Vasto Lorde form, not the hollow mask.
In bleach, bankai is a 5 to 10x multiplier. I am assuming that Ichigo gets the full 10x boost.
True Shikai Ichigo is equal to Mugetsu, as stated by Yhwach. Mugetsu was stronger than God/Monster Aizen, who was stronger than Dangai Ichigo, who was stronger than AIzen's previous butterfly form, which surpassed all hollows and soul reapers, including Yamamoto, whose bankai threatened the existence of soul-society, a planet-sized dimension, as Soul Society is said to be a replica of earth.
Therefore, assuming that Mugetsu was a 2x multiplier from Dangai Ichigo, then Ichigo is upwards of 20,000x planetary level. I am unsure if this counts as Multi Solar-System or Galaxy lvl.
If there are any flaws in my reasoning, please let me know.