The aforementioned languages form a certain language union, although they belong to different language families and even branches.
The languages in question are all the Scandinavic languages (Swedish, Norwegian, Danish, Faroese, Icelandic) plus Finnish and Estonian.
The phonetic phenomenon in question concerns vowel-initial words with a glottal stop preceding a vowel in an initial syllable.
In some isolated Swedish words the initial glottal stop is sometimes perceivable, and sometimes not.
The Danish glottal stop is likely to be an entirely different phenomenon.
In Seto and Võro, until recently regarded as dialects of Estonian, a glottal stop corresponding to Finnish Nom. Pl. marker -t (Estonian -d) is rendered with a letter q. That sound, however, (always?) takes a word-final position.
A glottal stop is sometimes perceived and articulated, and sometimes not, in Finnish vowel-initial words.
Are there any resources / researches regarding initial glottal stop in Norwegian and Faroese languages?
Does Swedish initial glottal stop really exist (as that is the case with German and, to some extent, in Dutch)?
Is there a similar phenomenon in Icelandic?