I would like to use "sethdseed" so all future pub and priv keys are derived from the seed I provided. Can I use the "importdescriptors" command to do that?
No. As BlackHatCoiner has explained above,
sethdseed command is only compatible with non-descriptor wallets.
If you want to use the
importdescriptor command to create an HD wallet, then your descriptor will need to include a master private key (xprv), rather than a WIF key. So you will need to use your manually generated entropy to generate an xprv first.