High Prio: Might want to use Cursor pagination (search up if you don't know) instead of offset pagination to reduce number of reads when scrolling the home page and paginating fetched posts.

Offset (?page=10&limit=20): Firestore reads docs 1–200, returns 181–200, bills you for 200 reads for that one page. Page 20 = 400 reads. Cost grows linearly with depth.

Cursor (?cursor=...&limit=20): Firestore jumps to the cursor and reads 20 docs, bills 20 reads. Same cost on page 1, page 10, or page 1,000.