You download the app and sends you surveys. They pay you for the surveys in Google Play Store credit. You can spend that on apps, in-app purchases, etc.
So, I have no idea what your patterns, habits, and just general life is like, but I actually use it for some subscriptions. I currently pay for Sync for Lemmy using it, and also for a mass texting app.
Are there any mobile games you like? You can use it for some iAP's :)
If there is an app that you've been eyeing but it is a little more than you'd like to spend, maybe use your credits on that!
That's how I paid for 1Password 7 a few years ago lol
I'm not the person you asked, but I find that making searches within YouTube generates a few (relatively high value) GOR surveys. I also get them when I walk near shops, but much lower value, especially as I usually didn't go into the shops it's asking me about.
In total, I've earned £134.39 since 2014 - not loads, but enough to mean I rarely pay real money for an app.
I like SeriesGuide for tracking shows and movies I watched, so I bought Series X unlock for it.
Other apps I've been happy with purchasing was swiftback up for backing up and restoring apps on rooted phones once Titanium Backup stopped getting supported.
Power Amp for listening to music.
1DM+ for downloading stuff from websites. It detects what are videos, pics, etc.
Hermit which makes lite apps. You can do that with Firefox or any browser for free, but I've liked hermit enough to get the pro version.
Got solid explorer and mixexplorer which are file managers.
Then there's some decent games like Stardew Valley you could buy.
And when you don't know what to spend it on you can donate money to some of the apps you bought, since some have in app options to send them donations.
I have an iPhone so it goes to my PayPal balance, which I used to pay for a lot of different online subscriptions so it just goes into the pot. It's $2 once every couple of months so I'm not exactly getting rich off it. When I had an Android I got a lot more surveys and I used it for premium features in Play Store apps.
I had the same problem and I just bought A Beautifully Foolish Endeavor audiobook because I'm on a 3+ week wait-list for the audio book from my library.
I used to spend it on IAPs for Pokémon go, but I've kinda stopped caring about it as much recently. Not sure what I'll start spending it on now. Guess I'll decide once I've save up a decent amount
Twitch streamer subscriptions. The rate at which I spend credits is higher than the rate at which I earn them, but I'm really happy every time I get an ad-free month on Twitch :)
I buy annual subscriptions to pokemon home with it, and microtransactions in games I play if I have extra. I would be buying pokemon home anyway, so it's a nice freebie
Cloud storage for your pokemon that lets you move them between the various games. You get one box of storage for free, so if all you want to do are some transfers, don't buy it, but if you play competitive and have more mons than you have convienient organization for, it's a must have. It's like $15 a year, so pretty achievable with the Google play rewards money