We just did an upgrade from 2019.x to 2020.2 and it worked beautifully. That’s some seriously nice work you’ve done there. One small thing, based on the minimum requirements listed here: https://octopus.com/blog/raising-minimum-requirements-for-octopus-server i was surprised to see that the upgrade-scripts did not set database compatibility level to 140.
Since you require SQL2017, it might be worth considering. I’ve done this manually, and so far it does not seem to introduce any issues.
ALTER DATABASE [Octopus] SET COMPATIBILITY_LEVEL = 140