Your fitting range is perfect for UP receiver with Sphere.
For Professionals - Phonak Audéo Sphere™ Infinio hearing aids | Phonak
However you’ll be in need of rather occlusive fit to achieve proper target gains especially in high frequencies and for boosting the efficiency of directionality and denoising features.
I do not buy the idea you need open fit because of ear infection. For what I know, no evidence suggest that with more occlusive fit and regular daily hygiene the risk is increased, especially when we talk about otitis media.
You didn’t specify, which infection you have - otitis media (zapalenie ucha środkowego) or externa (ucha zewnętrznego)?
Another option is just released ITE Virto Infinio R - the SP has huge reserve and can give MUCH gain even in highest frequencies