This supports Android Oreo without root, using Andromeda! If you have root, everything should work out of the box except on Samsung!
play.google.com/store/apps/details?id=projekt.andromeda

Support chat:
t.me/substratum (#support)

Take over control of the finest aspects of the system UI and personalise your Android experience without limits with the official Substratum theme engine, free to use and powered by the constantly growing, community-driven collection of beautiful overlays.

Attention:
Google is preventing stock OMS users from utilising custom overlays. To help us bring back rootless theming support to Android, please star the following issue in Google’s Issue Tracker: issuetracker.google.com/issues/74354703.

Theme engine support:
• Stock Oreo (OMS): Compatible with rooted and unrooted devices, in the case of the latter the Andromeda plugin is needed for Substratum to function correctly: play.google.com/store/apps/details?id=projekt.andromeda

Community links:
• Telegram: telegram.me/substratum
• XDA: forum.xda-developers.com/apps/substratum/
• Reddit: www.reddit.com/r/Substratum/
• CrowdIn: translate.projektsubstratum.com/
• GitHub: www.github.com/substratum
• JIRA (Bug Reports): substratum.atlassian.net/servicedesk/customer/portal/1

Detailed guide:
forum.xda-developers.com/apps/substratum/official-starting-substratum-andromeda-t3798316/post76687469#post76687469

Disclaimer:
Having external, third party theme clients installed may cause issues with Substratum, including unforeseen bootloops, crashes, and more. Customer support will refuse to provide assistance to users running such applications, including Swift Installer.

From version substratum theme engine one thousand twenty two:

Add compatibility with Android 10

All versions
substratum theme engine one thousand twenty two

Version:one thousand twenty two

Uploaded:October 15, 2019 at 12:00AM UTC

File size:7.48 MB

Downloads:7,574

substratum theme engine one thousand twenty

Version:one thousand twenty

Uploaded:April 24, 2019 at 2:46PM UTC

File size:9.45 MB

Downloads:14,962

substratum theme engine one thousand fifteen

Version:one thousand fifteen

Uploaded:December 15, 2018 at 5:30PM UTC

File size:8.69 MB

Downloads:20,752

substratum theme engine one thousand fourteen

Version:one thousand fourteen

Uploaded:December 15, 2018 at 1:55PM UTC

File size:8.69 MB

Downloads:937

substratum theme engine one thousand thirteen

Version:one thousand thirteen

Uploaded:December 9, 2018 at 4:12PM UTC

File size:8.69 MB

Downloads:1,224

substratum theme engine one thousand eleven

Version:one thousand eleven

Uploaded:December 8, 2018 at 6:42PM UTC

File size:8.32 MB

Downloads:829

substratum theme engine one thousand ten

Version:one thousand ten

Uploaded:November 9, 2018 at 10:58PM UTC

File size:8.41 MB

Downloads:3,692

substratum theme engine one thousand nine

Version:one thousand nine

Uploaded:October 28, 2018 at 7:17PM UTC

File size:8.41 MB

Downloads:2,172

substratum theme engine one thousand eight

Version:one thousand eight

Uploaded:October 27, 2018 at 10:54AM UTC

File size:8.41 MB

Downloads:784

substratum theme engine one thousand seven

Version:one thousand seven

Uploaded:September 21, 2018 at 9:37PM UTC

File size:8.4 MB

Downloads:4,363