Name: qogir-theme and qogir-icon-theme
Homepage/The source repository:

• Qogir-theme: https://github.com/vinceliuice/Qogir-theme
• Qogir-icon-theme: https://github.com/vinceliuice/Qogir-theme

Open source: Yes, GPL-3.0 license
Reason: Qogir-theme and Qogir-icon-theme are working perfectly on Solus Budgie, MATE and GNOME. They look great on Budgie too. Qogir-theme even supports GNOME 40 and GTK 4+.
The most up-to-date source file:

• Qogir-theme: https://github.com/vinceliuice/Qogir-theme/archive/refs/tags/2021-04-20.tar.gz
• Qogir-icon-theme: https://github.com/vinceliuice/Qogir-icon-theme/archive/refs/tags/2020-11-22.tar.gz