Is this a webdev only community? I see this being an issue in other development environments..
There are many ways to build local first, both with web technologies and with "native" app toolkits.
Many of the CRDT tools have started as JS/TS libs but have been rebuilt in Rust to be cross platform, WASM or native.
The appeal of using web tech is its accessibility and ease of distribution. Local first and PWAs with the new origin privet file system api kind of go hand in hand, but it's not an exclusive relationship.