I would like to add something related to how this topic related to SX. Social experience design starts from the perspective of each individual who participates in a commons, by means of Personal social networking. Social networking itself is defined as any human interaction between people, both online and offline. A person explores the commons based on self-interested motives and in hopes of improving their work / hobby / life balance. And this forms the foundation for collaborative arrangements and cocreation to take place.
With the above in mind, more friendly and natural terminology can be chosen, which will in turn help foster the culture for proactive participation in healthy commons, where we want to be part of.
Commons outreach
Instead of “self-promotion”, which has negative connotations (it fits ‘influencer-culture’ best), under Social coding commons and SX we speak of “Outreach”. To literally reach out towards peers in areas of the social network that relate to personal interests and passsions. And not on a one-time basis, but as a continual process, part of the FSDL (here in both its meanings, i.e. “Free software development lifecycle” and “Fediverse solution delivery lifecycle”).
With the social network representing mycelia, doing outreach means growing tendrils to seek out furtile connections, find nourishment, and exchange nutrients that help make the network stronger. This holistic notion of “outreach” helps in very deliberately get the most out of participation in any online network, in the pursuit of self-interests which provides the motivation to participate proactively. And being holistic also allows us to be strategic about this, which is only smart, with time and attention being the scarcest commodities on this planet. 
In the past I defined the concept of “Weaving in public”, which is helpful to anyone you weave for, while it helps increase your own luck and serendipity. A win-win situation, if done well. SX builds further on this concept and expands it to become 
Weaving in commons. Weaving in commons adds a third win when synergies from the commons based affiliation network are tapped into, and taken into account. To track and evolve these, SX defines the concept of a 
Triple win.
These concepts to be elaborated in due time..
For this topic, yes you can do “self-promotion” on Lemmy, but the larger realization is that ANY communication online constitutes you doing outreach in hopes to get the most out of your time spent online. And how that self-awareness allows you to be very deliberate about the nature of your communication and time expenditure in particular channels.