The question is, what do you understand under the term "fully open source installation". According to the quotes below [1], one can run KVM based virtual machines on this hardware, so at least everything based on RHEL and Ubuntu should run out of the box with install-ns [2].
About the learn production environment used for OpenACS/DotLRN: Around 2005, we switched from Intel Hardware to a p570 POWER5, later POWER6 architecture due to the significant better memory bandwidth at this time (PostgreSQL has a large memory footprint, which can be updated by many cores, forcing bandwidth hungry cache refresh operations) [3,4]. Around 2012, we switched on the main learn configuration back to Intel E5-2670, later E5-2699, now we have a two processor Xeon Gold 6154. Therese changes were mostly due to the improved memory bandwidth by Intel and better pricing of the commodity hardware. We are using on these machines CentOS + KVM.
In short, we were never using LinuxONE which seems to be based on the zSeries. However, since it supports KVM + RHEL etc. there should be in principle no problem, everything in the VM can run be freely configured. If i read correctly, KVM seems to be available on all LinuxONE servers [5], so this looks ok. I would still ask your friends about more details on the installation, there are probably various options in certain installations in terms of bought software features and/or site policies etc.
Hope this helps
-g
... IBM LinuxONE supports multiple Linux Distributions such as Red Hat (RHEL), SUSE (SLES) and Canonical (Ubuntu). Virtualization capabilities are delivered by KVM or IBM z/VM® hypervisors.....[1]
[1] https://www.slideshare.net/DiegoRodriguez322/ibm-linux-one-66359518
[2] https://openacs.org/xowiki/naviserver-openacs
[3] https://openacs.org/forums/message-view?message_id=340370
[4] https://openacs.org/forums/message-view?message_id=3588933
[5] https://www.ibm.com/support/knowledgecenter/en/linuxonibm/liaaf/lnz_r_kvm_base.html