So in a cadence, is it allowed to use a I64 chord to go to a V chord as a Half Cadence?
Yes it is "allowed"... I wonder what are your concerns about it? Actually, if you google "half cadence example" the very first result will use I64 chord: https://dictionary.onmusic.org/terms/1649-half_cadence
Well, nothing is prohibited about this chord change!
I would like to put in a quick word to the effect that some theorists may prefer to view the cadential I64 chord as a big suspension of the V chord, so in their eyes it might not be the exact same thing as a half-cadence (by that thinking, there's only one chord, so not a cadence). However, that is splitting hairs. In Common Practice Era harmony, one of the most compelling use cases for the second-inversion tonic chord is to lead directly into the V chord!
And of course, when the V chord ends a harmonic sequence, alarm bells sound in the head of counterpoint enthusiasts everywhere. When a cadence ends with the dominant, no matter what chord preceded it, that is a Half-Cadence. So the example of I64 - V absolutely counts as a half-cadence!
The last two chords are the telling ones with (most) cadences. With a half cadence (imperfect cadence), though, the telling one is the last chord. It must be the V chord. What precedes that doesn't really matter, as long as the sequence finishes on the V.
So just about any penultimate harmony is acceptable, although some will sound distinctly odd - even though their presence will not change the fact that there's an imperfect cadence there.