What devices to put into Excluded Devices list?

While my game is live I am still learning about the performance of the game. I already know that my game (because of the engine or something else) is quite exacting to the specs of the devices. For example, it's great (about 55fps) on iPhone 7 and iPhone 6s. Often crashing after loading the next scene on Samsung S5 Neo, iPhone 5S, and iPad Air 2. If I compare these devices (https://www.gsmarena.com/compare.php3?idPhone1=7242&idPhone3=8064&idPhone2=6506) I can see that the main difference I can notice between them is CPU. It seems that with CPU higher than 1.8 GHz everything is fine. Google Play, strangely enough, suggests filtering devices by RAM, which in all of these devices is the same 2Gb. So, what should I do? How to filter out the week devices with lower than 1,8 GHz CPU? What am I not seeing in my comparison?

I'm also curious if I can put some restrictions on downloading for iOs.
As I can see the best devices for me starting from iPhone 6s and iPad 5th gen. (2017)  are all using iOs 13. So I guess I can limit my ipa with iOs13. The problem I see that iOs 13 is only a couple months old and it makes sense to include some old systems, like iOs 12.4 which is the final system for iPhone 6 and it's almost a 1 year old. What do you think? Is it a good idea to restrict the minimum version with iOs 12.4?

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