Obsolescence Guaranteed makes replicas of classic DEC computers, such as the PiDP-10 and PiDP-11, and documents Arpanet and PDP-1 history.
HN commenters recommend its Raspberry Pi-based PDP replica kits, with working switches and LEDs, and note FPGA options for the PDP-11.
See also,
https://obsolescence.wixsite.com/obsolescence/pidp10
Relevant links,
PIDP-10 SYSTEMS USER’S GUIDE
https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fobsolescence.dev%2Fpidp10-sw%2Fmanual.docx
(direct download: https://obsolescence.dev/pidp10-sw/manual.docx)
PiDP-10 system software package (https://github.com/obsolescence/pidp10)
Obsolescence Guaranteed makes a PDP-11 replica [1]. At the heart is a Raspberry Pi running emulation software. All switches, LEDs are physical—all wrapped up in a clever case that looks like the original.
I have bought a couple of their kits and can vouch for the quality of them.
[1] https://obsolescence.dev/pdp11.html
I've got a PiDP-11 from the same group. It's a faithful replica, and it brings back memories from 50 years ago.
https://obsolescence.dev
It depends, for the PDP-11, you can plug a FPGA https://obsolescence.dev/pdp11.html