what altcoin do you mean?, as I know Top altcoin on market cap already had a mobile wallet application. If a new project only forked where the mobile wallet isn't ready yet, they must modify themselves and create new innovation for that. This means we should far away from the new project because they don't have a strong team yet, it could be a fall in the market cap.
Hardware wallet is the best, but if you can't afford it,
you can conecting hardware wallet into a mobile phone, but the problem is the new project didn't have that option.