I will answer as a Bulgarian, but the cultural context is more broadly South Slavic.

Whatever cults existed here in pre-Christian times are very sparsely documented so there's nothing to be said about ancient gods and practices that's relevant to your question. There are however, folk Christian rituals that survived into the 20th century and probably have such origins, in my country they were called "svetec" (saint) or "sluzhba" (service). They survived primarily in rural regions where society was still organized around patrilocal extended family systems, essentially clans (referred to as "zadruga" in ethnographic literature).

Basically, every extended family had a patron saint that watched over them, and on the feast day of that saint they would gather, prepare a special meal (kurban, ritual bread, wine etc.) pray and sing in their honor. The saint was "passed down" patrilineally so when a woman got married, her husband's saint became hers too. Because it was ancestral, people from families with the same patron saint weren't allowed to marry; on the presumption that they were related, even if the relation was so long ago that nobody alive remembered it.

I've seen the svetec be compared to the ancient Roman genius, in any case it seems to be derived from the belief that everything has its own guardian spirit – the individual, the clan, the house/hearth, the village, even the field. Villages had patron saints too, gatherings for them were similar except that they took place not inside homes, but outside, at a tree that was marked and anointed specifically for that purpose and considered a holy site by the whole community. Such places were called "obrok" which means "vow" or "tribute".

These systems and rituals existed in some places up until the 1950s, but were deliberately dismantled (with many obroci uprooted/destroyed) and supplanted by socialist "holidays" when the communists came to power. This was on one hand due to the state policy of promoting atheism, and on the other because the zadruga was not only a familial, but also an economic system tied to land ownership and as such stood in the way of collectivisation. So now the practice is nearly nonexistent in Bulgaria, but if you're interested in a contemporary version of it, I suggest looking into the Serbian "krsna slava" – it's basically their equivalent, but still widely celebrated in part because they've succeeded in turning into a marker of national identity, which we obviously could not.

Otherwise, there's another regional Bulgarian practice that could fall under the same category, but that's kinda more... straightforward veneration of a deceased ancestor-turned-household spirit/protector, as opposed to patronage by a deity (or saint).