lay person doing sermon a TLM

[The_Harlequin_King]

Well for one, aren't laypeople to not enter the sanctuary during Mass? (servers excepted)

It was customary in some countries before Vat. II that a priest would read the readings in Latin silently while a layman read the vernacular translation

From the sanctuary?

If there's a lectern inside the sanctuary, then sure. The lectern is a podium that's distinct from the pulpit, usually less elevated and on the Epistle side of the church.