Since I couldn't filter by community because the method used in my previous post failed, and I didn't want to touch the DSpace source code, I was able to filter the community for that set (without any filters) by using the community name in the set definition (the set name is snrd). (This also seems to work with collection.)
So, for future reference in the future, in my xoai.xml file in the <contexts> section I add my context:
<Contexts>
<Context baseurl="request" name="Default Context">
......
<Context baseurl="snrd" name="SNRD Context">
<!-- Date format, field prefixes, etc are ensured by the transformer -->
<Transformer ref="snrdTransformer" />
<!-- The snrd filter -->
<Filter ref="snrdFilter"/>
<!-- Just an alias, in fact it returns all items within the driver context -->
<Set ref="snrdSet" />
<!-- Metadata Formats -->
<Format ref="oaidc"/>
<Description>
This contexts complies with SNRD rules.
</Description>
</Context>
<Contexts>
In the <Transformers> section add my transformations..
<Transformers>
........
<Transformer id="snrdTransformer">
<XSLT>transformers/snrd.xsl</XSLT>
<Description>SNRD context transformer</Description>
</Transformer>
</Transformers>
In the <Filters> section add my filters
<Filters>
........
<!-- this works with my setup -->
<Filter id="snrdFilter">
<Definition>
<And>
<LeftCondition>
<!-- This condition determines if an Item has Bundle dspaceItem.getBundles("ORIGINAL") o algo asi-->
<Custom ref="itemsWithBitstreamsFilter"/>
</LeftCondition>
<RightCondition>
<And>
<LeftCondition>
<!-- This condition determines if an Item is publicly accessible. -->
<Custom ref="itemAccessCondition"/>
</LeftCondition>
<RightCondition>
<And>
<LeftCondition>
<!-- This condition determines if an Item NO es privado/retirado -->
<Not>
<Condition>
<Custom ref="itemWithdrawnCondition"/>
</Condition>
</Not>
</LeftCondition>
<RightCondition>
<!-- This condition determines if an Item tiene en entity.type sea Publication/publicaton -->
<Custom ref="isPublicationEntityCondition"/>
</RightCondition>
</And>
</RightCondition>
</And>
</RightCondition>
</And>
</Definition>
</Filter>
</Filters>
And now in the <Sets> section, in the definition of my set, I add the keyword/tag <spec> to match the desire community:
<Sets>
........
<Set id="snrdSet">
<Spec>snrd</Spec>
<Name>Conjunto de recursos para Sistema Nacional de Repositorios Digitales, Argentina SNRD</Name>
<spec>com_628872547_28240</spec>
</Set>
</Sets>
After restart and running "[dspace]/bin/dspace oai import -c -v"
I found the solution while chatting with ChatGPT; I couldn't find the solution in the documentation. I
And I don't know why it works. I hope it's not unintended behavior and I can use it safely...
I hope this helps those working on implementing the snrd set in OAI for use with digital repositories in Argentina.