Can a Deacon be referred to as a Lay Pastor?
Technically, a deacon is part of the clergy by the Sacrament of Holy Orders they are invested with additional grace.
In the past, Deacons were capable of becoming Pope.
Pope Leo the Great, was a deacon before he had become Bishop of Rome.
According to wikipedia "Deacons assist priests in their pastoral and administrative duties, but often report directly to the bishops of their diocese. "
While they do seem to have a "pastoral" role, legally and technically the "pastor" of the Church is the fully ordained and licit Priest.
A "lay pastor" is technically incorrect because of the fact that Deacons are not laity they are clergy this is clear from Canon 276, 2,3
usccb.org/beliefs-and-teachings/what-we-believe/canon-law/complementary-norms/canon-276-2-3-priests-and-deacons-and-the-liturgy-of-the-hours
Complementary Norm: Permanent deacons are required to include as part of their daily prayer those parts of the Liturgy of the Hours known as Morning and Evening Prayer.
Permanent deacons are obliged to pray for the universal Church. Whenever possible, they should lead these prayers with the community to whom they have been assigned to minister.
All clergy are required to pray the Liturgy of the Hours to unite them in prayer and reading. It is optional for laity to pray the Liturgy of the Hours.
If you want to learn how to pray the Divine Office, I like the Rule of Saint Benedict as a model.
And technically Deacons are not Pastors as the Pastor has a partaking in the role of the Head or Persona Christi in the Church.
While the Deacon is definitely consider to be part of the Body of Christ not partaking in the Head or the Leadership aspect of the Church.
The Pastor is the Shepherd of the Sheep.
Jesus was the Good Shepherd who laid His life down to give us divine life.