Propper tubelss tyres are stronger, but also weigh a lot more. 2bliss, tubeless ready, etc are a compromise that works well IME.
Get some superglue in a needle/syringe type bottle from a modeling shop and put a dab inside the cut to hold it together. Works half the time.
I found that an easier way to repair them than the whole cleaning faff was to cut a square of material about 15mm square (or bigger than the hole if it’s a big hole), really doesn’t seem to matter what, rubber glove, innertube, old bedding/t-shirt, bit of gaffa tape, clean the inside of the tyre arround the cut, apply contact adhesive (evo-stik etc) sparingly to the patch and the tyre and squeeze them together. It doesn’t need to be perfect, it’s just giving the sealent something to coat and seal that isn’t pulling apart like a cut. Works the other half the time.
If it realy doesn’t seal then sew up the cut with a needle and thread and apply superglue libberaly, then patch it.