There are quite a few remote or app controlled cock rings now. The only one we have first hand experience with though is the Lovense Diamo which should be fantastic but disastrously was way too small for my OH so it never got as far as a run out in public. I’m very temped by the We-vibe Bond being adjustable but can’t comment on noise levels or whether cock rings works out and about as yet.
Love eggs and knicker vibes we have a lot more experience with. Personally I wouldn’t buy the knicker vibes that come with knickers as they are generally not practical for wearing out under regular clothes. I have quite a few of the Lovehoney Mindful Seamless Thongs bought when they used to come as part of the Bra Set and they have a perfectly positioned pockets ready made for knicker vibes though of course with basic sewing skills a pocket can be added to any knickers your wife likes to wear out. My favourites knicker vibes are the Juno and the Mantric but it is essential with both that you have a perfectly placed snug knicker pocket to keep them in just the right spot!
Eggs wise, it’s worth spending a bit more and getting a decent one with stronger vibes that has a good remote range - read the reviews to find out how good the remote ranges are before buying! I got the FSOG Relentless Egg many, many years ago and it still works great and is my most used… it also happens to be 50% off now so if you don’t mind a remote controlled rather than app controlled I’d pick that one.
Knicker vibes are stronger feeling and more effective but they are also much louder so you generally need a busy venue like a loud bar or club to use them. If you’re new to remote/app controlled toys out in public I would pick an egg first to be more discrete. Your wife is not going to orgasm from these out and about (or knicker vibes) but as foreplay and setting the mood for when you get home they are great.
If interested:
My review for the FSOG Egg
My review for the Juno Knicker Vibe