Across the Spider-Verse referenced Tom Holland's Spider-Man, but other live-action versions appeared.
The movie didn't need the MCU's Webslinger, but his absence was noticed given all the other Spider-Men in Miguel O'Hara's Spider-Society (Oscar Isaac). This may assist Spider-Verse 2.
Miguel and Doctor Strange call Tom Holland's Spider-Man the "little nerdy kid from Earth-19999" in Spider-Man: Across the Spider-Verse.
Spider-Man 2099 was referring to the MCU's multiversal catastrophe triggered by Strange and Parker in Spider-Man: No Way Home.
2099's explanation of canon events throughout the interconnected Spider-Man-centered realities on the Web of Life and Destiny featured both Andrew Garfield and Tobey Maguire's Spider-Man.
Holland's Webslinger doesn't make a cameo exploring one of his canon events, which is excellent.
Across the Spider-Verse's creators have implied that Tom Holland's absence was purposeful, not contractual or legal.
This suggests that Lord and Miller chose not to include Tom Holland's Spider-Man in Across the Spider-Verse rather than Sony Pictures forbidding it.