As usual, the error was on my side.
The following steps are necessary to use LVM-volumes on dCore-bionic:
- sce-load lvm2. On its own, it is not functional as it is missing dependencies like liblz4 etc.
- sce-load wireless. Provides the missing dependencies.
- sce-load raid-dm-<KERNEL>-tinycore64. Provides and loads the dm_mod kernel module.
- vgchange -ay
Steps 1-2 give a functional set of LVM-tools. Step 3 introduces device mapper. However, it does not automatically activate the LVM-volumes as I had expected. This needs to be done manually as in step 4.
This is a bit a work-around rather than a fully automated set-up. Especially step 2 is not very intuitive and could be replaced by a dependency to lvm2. Though, as long as I am the only one using it or, respectively, others using it are happy with this approach, it is quite alright. Together with cryptsetup, things are working as I had hoped.