I don't think mobile games are going to get you anywhere near the potential you could get with PC or console gaming. However, doesn't mean that you wouldn't get following, just a smaller one. It also depends on the type of game. I'd recommend playing popular games that people would probably search up. And take this in to consideration: if you do switch to console gaming after getting an audience from mobile games, will they still enjoy your content? Hey, but since there aren't a lot of Youtubers that focus on mobile gaming, you could give it a shot. Good luck!
The potential may be higher but the market is more saturated. You can't just play games you want to play and make it to the top in pc or console gaming. You do that and your channel is a guaranteed hobby. You got to find new games that will have a following on this platform. Know enough about SEO to grip onto as many search phrases that get search volume to get on the 1st, 2nd, and even 3rd video page sometimes.
When I ran a "funny moments/gaming montage" channel, one of my most viewed videos that got me active subs was a melonbomber one. We were playing gmod murder in my friend's live stream on twitch. The people who made murder made the melonbomber gamemode so they update murder right when melonbomber was released to say "check out melonbomber".
So we did and we hopped right on it. I uploaded a video and I was on 1st, 2nd and 3rd pages for different search phrases to find the same type of content. Eventually I got pushed out for the established people but it took a while for the algorithm to settle them down. So I got some good views in the mean time.
Still I didn't really have the budget to go after repeat successes like that. But if you want to succeed in let's plays and funny moment world than you got to. You're not playing what's fresh then good luck exponentially growing enough to be a success on this platform.
-------------------
Mobile gaming is more obscure. You can do more development and pre production planning to capture a market or create one. There's decent mmorpg's on mobile these days. It's not all about "clash of clans", etc... plus those mainstream mobile games that actually get tv air time have some established youtubers covering them. They're making a decent chunk of change too.
Also developers of mobile games are more likely to be on twitter looking for sponsorship opportunities. So if you get views than you can get some sponsorship money and not have to rely on ad revenue being de monetized for that video.