Lemmy users are strange, they want a free and open internet, and they think it cost nothing to run.
It's totally normal to expect the app dev to eat and afford shelter.
I also use Boost and I can tell you with a single one time payment, ads are removed.
It doesn't hide read posts permanently anymore which effectively breaks the browsing experience imo. I switched to Boost and aside from a lack of gestures it's pretty on par.
I still love Sync and use it every day, but it hasn't been updated in a year. Everything seems to be working fine, but I do think about when something breaks if it'll get fixed...
Do you know if the Raccoon devs read reviews on Google Play? I have a few suggestions and I've posted them in a review but if they only read issues from git or something similar I'll talk there too