I have some ideas for potential hackathon projects for myself:
Finish https://commons.wikimedia.org/wiki/User:TabulistBot which is essentially a persistent delayed query functionality. There is a bunch of requests for something like that.
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Figure out if and how we could do https://phabricator.wikimedia.org/T179879 - different capabilities (mainly timeouts) for some oauth'ed users.
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Set up data collection for labeling Wikidata prefix searches, so that we could do ML processing. Basically, we need a way to know which search result the user selected for that, and right now it's not easy to figure out from logs.
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Try to make some progress in https://phabricator.wikimedia.org/T190454 - making Wikidata prefix search search in both item and article namespaces. Would probably require diving deep into the guts of the UI, so not sure if I can do it, but would be fun to try.
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Try to dig into Blazegraph guts and fix some of the annoying bugs like https://phabricator.wikimedia.org/T168876
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Work on Geo-lookup service described in https://phabricator.wikimedia.org/T179991
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Port Yuri's implementation of tabular data binding ro WDQS https://phabricator.wikimedia.org/T181319 (can go very well with with TabulistBot task above)
That's what I have thought about so far, now I need to choose what I actually want to do :)