I'm reasonably certain no public domain English (or Latin, though less sure about this as I'm unfamiliar with this language) translation of all four volumes exist.

Franciscan Archive has a version of book 1 (80$ for CD), but book 2 was due to release in 2010, and hasn't so is probably a dead end

HS Augusburg contains some free text (but only some select text)

Les Enluminuries says:

The Sentences was the most important medieval textbook on theology. Surviving in numerous manuscripts, they are available only sporadically on the market (seven have changed hands in the last 30 years, some multiple times)¹

Which hints at the rarity of said manuscripts and value (also wikipedia only lists one translation)

Potential partial documents:

_{A digital scan document in Latin? on German? website (I believe this is one of the books or commentary)}

_{A digital scan of Latin text}

_{Lincoln's Cathedral Library contains MS 31, 230 but not digital²}

_{1 https://www.textmanuscripts.com/tm-assets/tm-descriptions/tm0772-description.pdf}

_{2 https://www.cambridge.org/core/journals/traditio/article/abs/an-early-version-of-peter-lombards-lectures-on-the-sentences/32069E4398E039BEFD48869BFC8000B6}

I'm reasonably certain no public domain English (or Latin, though less sure about this as I'm unfamiliar with this language) translation of all four volumes exist.

Franciscan Archive has a version of book 1 (80$ for CD), but book 2 was due to release in 2010, and hasn't so is probably a dead end

HS Augusburg contains some free text (but only some select text)

Les Enluminuries says:

The Sentences was the most important medieval textbook on theology. Surviving in numerous manuscripts, they are available only sporadically on the market (seven have changed hands in the last 30 years, some multiple times)¹

Which hints at the rarity of said manuscripts and value (also wikipedia only lists one translation)

Potential partial documents:

_{A digital scan document in Latin? on German? website (I believe this is one of the books or commentary)}

_{A digital scan of Latin text}

_{Lincoln's Cathedral Library contains MS 31, 230 but not digital²}

_{1 https://www.textmanuscripts.com/tm-assets/tm-descriptions/tm0772-description.pdf}

_{2 https://www.cambridge.org/core/journals/traditio/article/abs/an-early-version-of-peter-lombards-lectures-on-the-sentences/32069E4398E039BEFD48869BFC8000B6}