I tend to insert at night as it's come out during the day sometimes, gravity and moving around I suppose. Also if you're very dry it can drop out during the day. It sticks to the vagina wall better at night.
Vagirux is another Estradiol pessory the same as Vagifem but with a reusable applicator.
Imvaggis (estriol) sounds ok if you can tolerate the waxy pessary (Butylhydroxytoluene) I'm sensitive to some additives and can't use oils and coconut oil etc.
Also I like the fact I can apply the Ovestin externallly where needed. I think it helps having both estrogens too, estradiol in Vagifem and estriol in Ovestin as they target different receptors. I've tried both separately but get better results using both together.
That's a shame you can't do the kegels, I found yoga helped, especially the cat cow exercise, I could feel the prolapse pulling in.
You can use YES internally and externally.