I managed to install libreboot on both a old 2007 Macbook 2,1 and a Thinkpad X60s. The macbook has a broken monitor and DVD drive (which explains how I got off ebay for <$50), but that is ok since I’m putting in two 1TB drives so I can use it as a fully-libre parabola linux server!
Broken screen adds cool effect. And here is the X60s (aka “libreboot X60s”) booting:
Added obligatory stickers: