What Mojang confirmed
The Minecraft LIVE recap says the dimension is coming to both Java and Bedrock next year. The cited announcement does not give a Bedrock beta build, release date, portal recipe, or confirmed feature list.
Why Java files do not work
The Mielon releases on Modrinth are Java .jar mod files tied to loaders such as Fabric, NeoForge, and Forge. Bedrock uses a different content system. Changing a file extension or copying the .jar into a Bedrock folder will not make it compatible.
Community Bedrock add-on
trotamundos872 publishes The Sift Dimension | Add-On as a separate beta project on CurseForge. The author describes clearing sculk from the Ancient City portal and lighting it with flint and steel, or using /the_sift:travel. These are add-on mechanics, not Mojang’s confirmed Bedrock entry method.
The creator’s own guide says the add-on requires both its Behavior Pack and Resource Pack. CurseForge lists separate 0.3 BP and RP .mcpack files. The creator describes floating islands, custom Sift forests and Sift Rabbits; these are add-on features, not confirmed vanilla Bedrock content. Check the current supported Bedrock version before installing; this site has not playtested the packs.
What to follow
Follow Minecraft.net for official Bedrock progress. Use the creator’s CurseForge project and file pages for the separate beta add-on; its updates do not predict Mojang’s release.