The second of Luther's three church missions is delivering sacraments, one of which is communion. Somehow prayer never gets top billing as a sacrament, but it seems as if it should. Prayer itself is perhaps the most pure of sacraments. Glossing over this sacrament, let's consider communion.
The physical manifestation of communion appears to be a blessing of bread and wine, followed by waiting in line, giving of the bread and wine, receiving of bread and wine, an exchange of words and a contemplative walk, returning to one's "place." We Protestants are blessed to consider the bread and wine as symbols and not as literal spiritual manifestation impossible to share without shared physical space. Otherwise, perhaps the congregant could receive this week's wafer and even wine as blessed but mailed the week before. In this pandemic, we have foregone the blood of Christ and added hand sanitizer.
The online manifestation would ideally reproduce these very steps: waiting in line, receiving the sacrament, returning to the pew in meditation. The careful maneuver would be inviting the congregant to leave the space after the blessing. At physical communion, the congregant initiates leaving. The congregant would perhaps prepare the bread and wine and present it to the reverend for blessing. The difference being that perhaps the congregant would be virtually inviting the Reverend into the congregant's sacred space. This can be achieved by allocating the congregant to a separate room to wait for the clergy to come and give communion after which the congregant would return to the main meeting then to the sub-meeting with the computer in place for the pew at which the congregant would be virtually seated.
Along with the Lord's Supper, we Protestants only need worry about baptism for the official sacraments. For now, I will only consider that virtual attendance would not include the person receiving baptism. It is fully fitting that we do consider remote baptism for online participants as an eventuality, but not now, not here. For the ceremony, simply consider the configuration to include hybrid physical and virtual meetings. For the preparation, the meetings would be straightforward if the interview involves just one pastor and one congregant. Should multiple congregants be involved, it would be best to ask each congregant to be on a different terminal in a different place. Even with two congregants, it is very unlikely a hybrid meeting with the equipment available to the congregants would allow for the requisite intimacy.
In the beginning of the pandemic, the American Church would deliver communion by video. There was no other way, and we would receive the blessings in this manner. Now, perhaps we can ask the question if communion and/or baptism, as sacraments, can be delivered with spacial and temporal distance. Reflecting on Luther's letter only, I would tend to think there need be an element of conscious submission on the part of each party involved.
Confirmation, ordination and marriage are pseudo sacraments with heavy implications for "augmented reality." (Isn't religion itself the initial augmentation of what we first were born to accept as reality?) Each could be considered in the context of appropriateness to technology. In each case, the church body is the community through which the sacrament has earthly grounding.