Good news is that they just added a plan stability feature in pg19. It's actually full planner hints, so you can edit the plan to whatever you want if you have no fear, but the main motivation is exactly index stability.
replyI looked it up because I'm interested in the subject but it seems it's only a proposal right now? At least according to this 5 month old blog post https://rhaas.blogspot.com/2026/03/pgplanadvice-plan-stabili...
replyEdit: Never mind, found it https://www.postgresql.org/docs/19/pgplanadvice.html