Cuckoldry must (in being true to the root of the term) involve being deceived in some way related to sexual idealism.
Obviously you are not deceived about whether she is using the toys: you are "letting her" and are aware she is using them.
So for this to be cucked it must involve some other kind of deception related to these dildos. For example...
1) "she likes my dick more than the dildo" when she doesn't
2) "she won't devalue me as a result of getting proficient with this" when she would
So ultimately whether or not you're self-cucking depends on how good your dick is at pleasing her.
If you're super great and the dildo never measures up, then it's not cucked.
If she enjoys it too much and thinks you're less important, and you expected otherwise, then you cucked yourself.
OTOH if you pretty much expected her to rely on you less and maybe even like the dildo more, and went along with it anyway... then you knew what you were getting yourself into (no deception) so it's not cuck, just romantic suicide.