FWIW, USNF (now w/ @Displax' mods) is the defacto replacement for basic MagiskHide functions that provided an environment attestation API (SafetyNet) bypass...I could be wrong, but for most people, the "solid base" of Magisk modules (assuming stock ROM with root) is just USNF Displax mod. If other modules or modifications are installed then more elaborate hiding measures might be necessary but in general the modded USNF alone is sufficient to pass basic and device integrity.
MagiskHide also provided proper 'root' hiding from apps but always remained basic as John has tired of / lost interest in bypassing app's increasingly sophisticated custom root trace detection methods for some years now.
This has meant that more sophisticated root hiding has been the province of solutions like
'Servicely' (to disable services with isolatedProcess enabled that can 'easily bypass MagiskHide), vv's Unshare and later Canyie's MomoHider Magisk modules in combination with Magisks own hidelist.
XPosed modules like Hide My Applist were also added to the list of hiding solutions as Devs have found ways to (arguably) abuse ability to detect apps they deem indicators of execution environment compromise despite Google's efforts to limit this 'improper' use of permissions like QUERY_ALL_PACKAGES...
With Zygisk-generation Magisk (24+), even basic root trace hiding has been 'sunsetted' in Magisk itself... As John said:
• It's not a secret that specifically designed modules can indeed utilize the DenyList feature for "hiding" purposes
• DenyList, however, is only meant to "revert all Magisk changes". It will not attempt to manipulate any other signals on the device
• Since Magisk already provides root permissions, modules don't actually need to rely on DenyList for hiding. They can do everything themselves
• There are already modules out there that directly manipulates root detecting processes / system services to workaround HW KA
So newer efforts to provide root hiding have had to re-implement proper methods (not simply reverting Magisk modifications in processes which actually breaks much hiding). This means that solutions like Shamiko, while 'hijacking' denylist for convenience, are actually re-imlementing denylist as a hidelist. In this sense at least Shamiko is now supplying the 'solid base' hiding once provided by MagiskHide (but it's not needed for passing SafetyNet or Play Integrity attestations as you said)...
Of course other 'base' hiding is also supplied by Shamiko, eg xhook hiding for LSPosed and other modules was previously integrated in Riru as Riruhide but many were unaware of its existence. With 24+ Magisk there is no such integrated hiding but Shamiko is hiding (most?) traces of xhook/Zygisk now...
Being a Canyie initiative, Shamiko adds the unshare (isolated process) and other hiding done by her MomoHider as well as tmp mount and more hiding for further traces now detected by banks... PW