It’s nearly impossible to use Logseq without a keyboard. There is mention of a mobile toolbar, but even the row of icons above the Virtual On-Screen Touch Keyboard doesn’t appear in the latest version on the web interface, at least on test.logseq.com.
The answer seems to be Hacker’s Keyboard from F-Droid App Store. Not the one on Google Play Store. This one has [ESC] icon. It does support many (though I haven’t tested them all) of the key combinations. Even better, you can configure swipe-left and swipe-right gestures to bring up a bar of function keys (F1-F12), or swipe the other way and it comes up with a list of suggested punctuation marks. You can add your own characters.
It doesn’t support emojis; they come up as pairs of question mark icons. It does seem to support Unicode characters, although you may have to paste them into the config.edn file by hand.
One problem is that the keyboard is not always present, particularly in the Keymap Settings dialog that says “press any key combination.” The solution is that there is an option to have a permanent notification, which will instantly bring up the keyboard even when it is not really needed.
Of course, there are also Bluetooth keyboards.