Based on older comments here, and much more recent ones in the NextPVR forum, it looks like some folks have had success with this, but I can't find an actual working template from the last 2 years.  Anyone willing to share one?

Fixed it myself.  In case this helps others, here's my template, through you'd want to verify the network type and paths match what you want. 

 

<?xml version="1.0"?>
<Container version="2">
  <Name>NextPVR</Name>
  <Repository>nextpvr/nextpvr_amd64:stable</Repository>
  <Registry>https://hub.docker.com/r/nextpvr/nextpvr_amd64</Registry>
  <Network/>
  <MyIP/>
  <Shell>bash</Shell>
  <Privileged>false</Privileged>
  <Support/>
  <Project/>
  <Overview>NextPVR TV recording and video player software.</Overview>
  <Category>MediaApp:Video</Category>
  <WebUI>http://[IP]:[PORT:8866]/index.html</WebUI>
  <TemplateURL/>
  <Icon>https://hub.docker.com/r/nextpvr/nextpvr_amd64</Icon>
  <ExtraParams>--security-opt=no-new-privileges</ExtraParams>
  <PostArgs/>
  <CPUset/>
  <DateInstalled>1695046806</DateInstalled>
  <DonateText/>
  <DonateLink/>
  <Requires/>
  <Config Name="Recordings" Target="/recordings" Default="" Mode="rw" Description="Recordings Folder" Type="Path" Display="always" Required="false" Mask="false">/mnt/user/media/recordings</Config>
  <Config Name="Buffer" Target="/buffer" Default="" Mode="rw" Description="Live TV Folder" Type="Path" Display="always" Required="false" Mask="false">/mnt/user/appdata/nextpvr/buffer</Config>
  <Config Name="Configuration" Target="/config" Default="" Mode="rw" Description="Configuration Path" Type="Path" Display="always" Required="false" Mask="false">/mnt/user/appdata/nextpvr/config/</Config>
</Container>