Do it. :)

No worries about incompatibilities like that.

Very low risk.

If you need something of some version from another stratum, you can just ensure that thing's installed, and/or run it with the restriction flag on strat (strat -r). The strata don't step on each others toes, it's all cleanly separated enough, and still allows interoperability.

Possible to achieve such thing easily. Yup.

Choose any init you like, from any distro.

While you'll of course only be running one init (and one kernel) at a time, at boot you do get to select which of them you want to run, ~ the kernel in the bootloader menu as usual, and the init system in bedrock's init selection menu just after the bootloader menu.

Whichever distro you use for the installer, that'll be your hijacked distro, and shall be default choice in the init selection menu for your init. Both can be changed later (or even removed ~ once you install at least one other distro & init).

About able to use Gentoo level's a fine indicator of able to use bedrock. Means can read documentation. That's necessary.