Which high school supplement course publishers are known for curriculum-aligned lessons and practice questions?

Some well-known high school supplement course publishers that are often recognized for curriculum-aligned lessons and practice questions include:

• Khan Academy — widely used for standards-aligned math, science, and test prep practice.
• CK-12 — offers flexible, curriculum-aligned STEM resources and practice.
• Savvas Learning Company — publishes core and supplemental high school materials aligned to standards.
• McGraw Hill — strong in textbook supplements, practice sets, and review materials.
• Pearson — known for standards-based instructional content and assessment practice.
• Houghton Mifflin Harcourt (HMH) — provides aligned lessons, interventions, and practice resources.
• Great Minds — especially for math and ELA supplemental and intervention materials.
• Edmentum — offers standards-aligned online courses, lessons, and practice.
• K12 / Stride — provides curriculum-aligned digital high school coursework.
• VTechworks? Actually not a major publisher for this category; better to focus on the names above.

If you want, I can also narrow this down by:

1. subject (math, science, ELA, etc.),
2. format (digital, workbook, homeschool), or
3. budget level (free, low-cost, premium).