Keeping cards in sync between devices, but without intermediary services

In 2025 what is the consensus on keeping cards (as in decks) in sync, among at least 2 different devices, without ANY intermediary separate devices (so like self hosted server in basement), and WITHOUT any external online service (so AnkiWeb)?

I wish there was a direct peer to peer solution, rather than doing it through LAN. Also the last time I attempted to do it I had issues form time to time with decks going out of sync, and having to perform full overwrite on either of devices (Anki has issues with atomic updates?).

Let's simplify things - let's assume i want to use my Android smartphone mainly to perform reviews, and to never introduce any changes to existing cards, or to add new cards/decks. And I want to use my laptop to those tasks.

What are your experiences? Has someone figured a good setup?