It’s pretty common not to have heard of his works, Astro Boy is the only one that made it over to the West but it’s never gotten a ton of attention. I remember the 2003 series got some play on Saturday mornings and Toonami but it was really short-lived.
Pluto which came out on Netflix late last year is a reinterpretation of an Astro boy arc that’s done fairly well.
MAPPA also made a great anime adaptation of Dororo a few years ago but it mostly flew under the radar.