… I see nothing in the GIRM to suggest that the Prayers of the Faithful are optional, but the Sign of Peace is optional.
The GIRM has, about the Prayer of the Faithful:
“69. … It is fitting that such a prayer be included, as a rule, in
Masses celebrated with a congregation, so that petitions will be offered for the holy Church, for civil authorities, for those weighed down by various needs, for all men and women, and for the
salvation of the whole world.”
I think it is reasonable to interpret “fitting” and “as a rule” as “its encouraged, but optional”.
Regarding the Sign of Peace, the GIRM has:
“154. … Afterwards, when appropriate, the priest adds,
Offerte vobis pacem (Let us offer each other the sign of peace).
The priest may give the sign of peace to the ministers but always remains within the sanctuary, so as not to disturb the celebration.”
Also “181. … the deacon, if it is appropriate, invites all to exchange the sign of peace.” Also in “Mass With Only One Minister”: “266. … The priest gives the sign of peace to the
minister, if appropriate.”
So it seems that a decision can be made that the Sign of Peace is not appropriate, there should not be an invitation and it should not be made. (To look up the GIRM, go to
romanrite.com/girm.html )