I use Bookwalker, syncing between smartphone and tablet. It also syncs to PC, but I don’t usually read on that. Smartphone has convenience, while tablet has comfort. PC has VN and other materials.
The dictionary app is usually Aedict on smartphone, where it has more than JMdict and KANJIC (e.g. Proper Names, Bio-Medical). Also it is fully offline, but the contents get updated periodically. Searching is via either English keyboard (+ dictionary-dependent Kana guessing), Kana keyboard, or Handwriting keyboard (GBoard, actually). Kanji handwriting, afaik natively in any dictionary, sucks; also they don’t accept Kana handwriting.
Aedict entries also have a hyperlink to Goo in beginning-with mode. However, browsing Goo in mobile is worse compared to PC. Also it needs to be online. I don’t have an offline monolingual dictionary on Android.
Occasionally, there is no dictionary results. Aedict sometimes allows saving non-entries to History. However, Akebi, which I don’t use much nowadays, remember searching keywords (i.e. custom keywords).
Akebi can easily be popped up when reading on a mobile web browser. The downside is JMdict doesn’t get updated in this app.
When reading with tablet, I look up on smartphone; so it is easy. But when reading with smartphone, I need to switch apps, so it gets inconvenient sometimes. (Bookwalker grey out and resync on switching apps.)
Reading light novels on Bookwalker has Google Translate and searching on the web. However, it is nothing like a proper dictionary.
Yomichan is used when typing in to Discourse (right here) or Google Sheets; so it is manual for what I want to look up further. It is also used when reading on PC web browser, of course. Yomichan is the only means currently, for me to add to Anki (in suspended mode).