Do words with "ij" (strijf, whijt, prijs, wijf, lijf, lijk, chijld) relate to Middle English?

The question is a bit vague (since Wycliffe's Bible is from the Middle English time period, you seem to have answered the first sentence of your post with the second: these spellings do in fact "relate to Middle English").

The sign "j" started out not as a letter of its own, but just as a variant form of the letter I. In various languages, at various time periods, a convention has arisen of writing long vowels with doubled vowel letters; that convention is the source of the modern English digraphs ee and oo. The obsolete (in English) digraph ij basically comes from the same convention: it's a modified version of a double minuscule I, and represented a "long i" sound. The exact use of doubled vowel letters varied between texts in Middle English: they were not regularly employed in all contexts (often a single vowel letter was used to represent a long vowel), so the same sound might be spelled in different places as ij, i, y.

For whatever reason, ij fell out of use in English. As you can see from your list, historical spellings with "ij" mostly correspond to modern English spellings with "i_e", which are derived from the alternative convention of using a word-final "silent e" to mark a long vowel (or in the case of the word child, the length of the vowel is just not marked). Between Middle English and Modern English, long vowels came to be diphthongized, so Middle English [iː] became modern English [aɪ].

Wiktionary and Etymonline aren't the places to go if you want a list of spelling variants used for a word in Middle English. The Oxford English Dictionary has better coverage of historical spelling variants.

In a comment, John Lawler wrote:

That's a spelling convention that Wycliffe's editors shared with Dutch writers; it represents the /ay/ diphthong of English. But it didn't catch on in English, only in Dutch. English spelling is political, not linguistic.