Local first is really relevant if you have the potential of users losing connectivity or is building some sort of collaborative workflow and want updates to happen automatically (like Linear or Google Docs).

Latency is not a real issue with SSR apps, there are a bunch of solutions to place servers and data closer to your users (within a few tens of ms). Plus you can prefetch and cache content very easily without using service workers. That’s not the reason Jira or GitHub feel slow; in fact GitHub was quite fast a few years ago when all it did was render pages from the server.