Using the new version of the dist-upgrader I was successfully able to upgrade from Groovy to Impish.

bdmurray@clean-groovy-amd64:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=21.10
DISTRIB_CODENAME=impish
DISTRIB_DESCRIPTION="Ubuntu 21.10"
bdmurray@clean-groovy-amd64:~$ head -n20 /var/log/dist-upgrade/main.log 
2022-07-06 08:12:44,568 INFO Using config files '['./DistUpgrade.cfg.groovy', '/etc/update-manager/release-upgrades.d/ubuntu-advantage-upgr
ades.cfg']'
2022-07-06 08:12:44,568 INFO uname information: 'Linux clean-groovy-amd64 5.8.0-63-generic #71-Ubuntu SMP Tue Jul 13 15:59:12 UTC 2021 x86_
64'
2022-07-06 08:12:44,852 INFO apt version: '2.1.10ubuntu0.3'
2022-07-06 08:12:44,852 INFO python version: '3.8.10 (default, Jun  2 2021, 10:49:15) 
[GCC 10.3.0]'
2022-07-06 08:12:44,854 INFO release-upgrader version '21.10.10' started
2022-07-06 08:12:44,858 INFO locale: 'en_US' 'UTF-8'
2022-07-06 08:12:44,941 DEBUG Using 'DistUpgradeViewText' view
2022-07-06 08:12:44,984 DEBUG enable dpkg --force-overwrite
2022-07-06 08:12:45,029 DEBUG creating statefile: '/var/log/dist-upgrade/apt-clone_system_state.tar.gz'
2022-07-06 08:12:47,118 DEBUG lsb-release: 'groovy'
2022-07-06 08:12:47,119 DEBUG _pythonSymlinkCheck run
2022-07-06 08:12:47,124 DEBUG openCache()
2022-07-06 08:12:47,124 DEBUG quirks: running PreCacheOpen
...
bdmurray@clean-groovy-amd64:~$ tail -n10 /var/log/dist-upgrade/main.log
2022-07-06 08:37:51,460 DEBUG 'linux-image-5.8.0-63-generic' scheduled for remove but not safe to remove, skipping
2022-07-06 08:37:52,139 DEBUG skipping running kernel pkg 'linux-headers-5.8.0-63-generic'
2022-07-06 08:37:52,140 DEBUG 'linux-headers-5.8.0-63-generic' scheduled for remove but not safe to remove, skipping
2022-07-06 08:37:53,112 DEBUG Finish checking for obsolete pkgs
2022-07-06 08:37:53,165 DEBUG The following packages are marked for removal: ca-certificates-java libgssapi3-heimdal default-jre-headless l
iblibreoffice-java liborcus-parser-0.15-0 default-jre libedataserverui-1.2-2 libwind0-heimdal libridl-java libldap-2.4-2 libboost-iostreams
1.71.0 realmd libgdk-pixbuf2.0-0 libatk-wrapper-java linux-image-5.8.0-25-generic libpython3.8-minimal vino libraw19 gcc-10-base libjuh-jav
a libheimntlm0-heimdal xul-ext-ubufox libtracker-sparql-2.0-0 libamtk-5-common perl-modules-5.30 libheimbase1-heimdal libpython3.8 python3.
8 linux-modules-extra-5.8.0-25-generic libbrlapi0.7 linux-headers-5.8.0-25 linux-headers-5.8.0-63 libboost-locale1.71.0 libappindicator3-1 
ure-java libhandy-0.0-0 openjdk-11-jre-headless linux-headers-5.8.0-63-generic libisl22 libboost-filesystem1.71.0 libtepl-5-0 lz4 linux-hea
ders-5.8.0-25-generic libtracker-miner-2.0-0 libatk-wrapper-java-jni sssd-dbus adcli libperl5.30 libllvm11 libsnmp35 libboost-date-time1.71
.0 libboost-thread1.71.0 libjurt-java libfwupdplugin1 linux-modules-5.8.0-25-generic python3.8-minimal openjdk-11-jre ubuntu-wallpapers-gro
ovy libhcrypto4-heimdal fonts-dejavu-extra sssd-tools liborcus-0.15-0 mysql-common libmysqlclient21 libphonenumber7 libpython3.8-stdlib lib
tracker-control-2.0-0 libroken18-heimdal libpoppler102 firefox gdbserver libasn1-8-heimdal libkrb5-26-heimdal python3-requests-unixsocket c
pp-10 libcc1-0 libunoloader-java libgdk-pixbuf-xlib-2.0-0 libhx509-5-heimdal libedataserver-1.2-25 java-common gnome-getting-started-docs libamtk-5-0
2022-07-06 08:39:30,204 INFO cache.commit()
2022-07-06 08:40:03,503 DEBUG quirks: running PostCleanup
2022-07-06 08:40:03,503 DEBUG running Quirks.PostCleanup