Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
Nothing wrong with house churches—so long as a duly ordained priest or bishop presides over the service (like they did in the first century house churches).
I know that the Ethiopian Orthodox Tewahedo Church uses mandatory consecrated Altar stones, usually of wood but sometimes carved stone, called the Tabot
in plural) and no Eucharistic services can be performed without a Tabot. Further, only ordained clergy and deacons can either carry or even stand near the altar stone, so to put it in a house would I suppose at least have to comply with the church structure of the EOTC with three sections, the innermost being the "Qidus Qidusan" (The Holy of Holies) where only clergy can go. If a service were to be performed in a home, a Tabot would have to be present and I suppose also the architecture restrictions. When we have Timket services outside in a big tent, there is a inner section closed off.
Much of the Orthodox tradition suggests that, even if initially placed in homes, even in the first century the Apostles' had churches (ie, specially sanctified buildings used for Eucharistic services). It is even in the New Testament.
I know the Syrian Orthodox also have a wooden altar stone, the thabilitho, and before Vatican II, all Roman Catholic churches required a consecrated altar stone by a bishop for services, just as the tabotat
must be consecrated by a bishop.
Further, if you did bring a consecrated altar stone into a home chapel, permanently though, wouldn't you in a certain spiritual way really just be turning a home into a church? In the EOTC, it is precisely the Tabot
which makes the church building sacred and why we kiss the walls and the floors, we hold an Old Testament theology about the Church being the Temple, and the Tabot being like the Ark, and all the even superstitious sacredness attached to the Ark we give to the Tabot and any building, tent, or priest who is carrying it.