you could try a patch but I think it would be hard to make it invisible. Try to find some matching thread (slightly lighter if not an exact match). Put patch behind and then darn on top. Certainly a patch behind would support the fabric more so it be less likely to split. Cut your patch from inside a back pocket if want unless you have anything ales to hand.
could you get some bits of denim and patch them from the inside with iron on adhesive?
Then the knees are reinforced, and you don't neck. see the patch, and if the knees go, then all you see is denim not hole. Buy good quality iron on stuff though. The cheap stuff will drop off after a couple of washes.
i'm pretty sure the adhesive on those patches is on the back, so the would work by gluing them on top of the front of your jeans rather than on the inside ifswim. Not sure you want big dark patches showing on yr knees. Haven't read small print so may be wrong.
I use those patches and ironed them on the inside of my jeans (the right knee always seems to go first on mine). They stop the material from fraying and have helped extend the life of jeans by a few months. You just iron them adhesive side down on the inside. Much better than any patching/sewing.