For me the macOS/iOS text substitutions work very well.
They sync across all my devices, are fast and are available without switching keyboards on iOS.
For more advanced snippets I use Keyboard Maestro on the Mac, and just don’t use them on iOS.
I find using the TE keyboard and expansion of advanced snippets on iOS is weird, ugly and time consuming, and I usually just end up typing the text myself (usually quicker)
All in all it has been solid for me, and I have not missed TE. 