Experience joining a guided trek solo?

Hi all I am tentatively planning a mid december peru trip. I would love to join a guided trek (either sankaltay or asuangate). For those that have joined a trek solo what was your experience like? Any tour company recommendations (I am currently looking at IncaGo, AB Expeditions & Refugios Sankaltay). When I look at their websites I don't see pre-set trek dates so I am curious how you join a group as a solo traveler.

As a side note i am plant based so if you have any recommendations for a tour group you felt was accommodating to dietary needs let me know! I am not picky and am happy with rice, veggies and beans. I don't need anything fancy

Thanks in Advance!