There will be a reference to Space Usagi.
Yuichi will make a remark about wanting his descendant from a thousand years from now to be a famous spacefaring samurai.- Jossed. There's no reference to Space Usagi, at least in the first season.
The Teenage Mutant Ninja Turtles will be referenced at some point
Yuichi Usagi's lineage.
Usagi Yojimbo uses traditional Japanese naming conventions, meaning that "Usagi" is the main character's given name and "Miyamoto" is his surname. Miyamoto Usagi's only known offspring is illegitimate and publicly recognized as his stepfather's son, so he didn't inherit the Miyamoto name, and it's been centuries with plenty of other opportunities or reasons to change surnames over the generations.- Alternatively it's possible that Yuichi isn't a direct descendant, Miyamoto's cousin Yamamoto Yukichi was introduced in the June 2021 issue
with a visual design closer to Yuichi's.
The series is set in 2012 Usagi's future.
Miyamoto Usagi has the same voice actor as in TMNT 2012, which is also a CGI cartoon. The flashbacks are in 2D still images. And the alarm system in Yokai sounds similar to The Kraang's alarm. The main characters are Reincarnations of their namesakes from the comic.
Yuichi was Yamamoto Yukichi, since Miyamoto Usagi's spirit was trapped in the crystal. Which also explains the similarity in personality and looks.