The little stick kinds of tire pressure gauges are “okay”, but spend a few more quid and get a nicer one with a dial meter. They’re more accurate and less prone to breakage.

Next step up would be a battery powered inflator. I got a cheapy Ryobi one that will inflate a tire, though its battery (USB-C rechargeable and proprietary) is so small that it needs recharging after filling one really low tire. I’d recommend a larger one, but even something like that will save your bacon in a pinch.

Edit: Oh, and tread depth gauge, you might not find that super useful. Tires will have treadwear indicators on them, little raised bits in the grooves. When the tread and the raised bit are equal, the tire needs replaced. But make sure you’re feeling around the treads from time to time. Even regular use can cause front tires to “feather” (because the driving and turning are on the same axle), so keep em rotated. Misalignment, bad shocks or springs, worn steering/suspension components can also create uneven wear, and the tires can be the first place that shows.