Custom blockchain indexers are one of those projects that look like a week of work and turn into a quarter of work. Not because the core loop is hard, but because every edge case compounds.
"Just run your own indexer" is common advice in blockchain development circles. It's not wrong advice - but it undersells what "just run" really involves.
Every time you deploy a new Bitcoin indexer - or migrate to a new server - you face the same problem: you need to process 880,000+ blocks from genesis to the current tip. How you do it determines whether this takes 6 hours or 6 days.
Bitcoin has over 880,000 blocks. If you're building an indexer and need to backfill from genesis, your choice of transport protocol will determine whether that takes hours or weeks.