The articles sound interesting, particularly those about Plan 9.
So does TexiWeb Jr., a super simple literate programming system built on top of Texinfo and implemented in awk https://github.com/arnoldrobbins/texiwebjr
which is mentioned in
AWK As A Major Systems Programming Language — Revisited
http://www.skeeve.com/awk-sys-prog.html
struct --- Convert Fortran into Ratfor
could be useful for proot:
This is Brenda Baker's struct program. It converts plain old Fortran into Rational Fortran (ratfor). The code here is taken from the TUHS archives, starting with the V7 version, and progressing through V8 and V10.
https://github.com/arnoldrobbins/struct

This suite of open source tools is the software development platform you've been waiting for. We've taken the wisdom of the most successful open-source communities and turned it into a platform of efficient engineering tools.

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Sourcehut is currently (2020-09) available as a public alpha.
Note that it includes a Plan9(front) continuous integration service
https://sourcehut.org/blog/2020-05-11-sourcehut-plus-plan-9/

Recommended by Brett Gilio
https://brettgilio.com/posts/2020-10-01-why-self-host.html

Boot an UEFI machine over the network using the Plan 9 protocol.

Interim is an attempt to implement an operating system using ideas from the Lisp machines and Plan 9.
https://github.com/mntmn/interim
The blog has other interesting articles on (Emacs) Lisp, Scheme, git...

This post is a survey of technical and community issues connected to Plan 9 root file servers. The author is not a member of any Plan 9 tribe save Grid. Opinions are entirely my own and a lot of unsourced claims will be made based on my years of participation and observation of the Plan 9 community.

"ma" is a minimalistic clone of the acme[1] editor used in Plan 9, and is written in Tcl/Tk. It has been tested with Tcl/Tk 8.5, mostly
under Linux. "ma" has successfully been run on Mac OS X with XQuartz, but needs a tiling window manager to be used in a satisfactory way.

Description of an interesting operating system (not implemented yet) based on ideas from QNX and Plan 9.

Apart from the Scheme compiler Chicken
 http://www.call-cc.org/
two other Scheme and one Forth system, there is
 MA, a minimalistic variant of the Acme editor, written in Tcl/Tk.

Beginning with the Eighth Edition, ed(1) had the following command.
This is from the Plan 9 ed man page.

         (.,.)b[+-][pagesize][pln]
              Browse.  Print a `page', normally 20 lines.  The
              optional `+' (default) or `-' specifies whether the
              next or previous page is to be printed.  The optional
              pagesize is the number of lines in a page.  The
              optional `p', `n', or `l' causes printing in the speci-
              fied format, initially `p'.  Pagesize and format are
              remembered between `b' commands.  Dot is left at the
              last line displayed.

Plan 9 from User Space moved from http://swtch.com/plan9port here. See also the Google discussion group https://groups.google.com/forum/#!topic/plan9port-dev/OqSvUDfwS-M.