Just note that with Bambu printers about past data collection practices and their in general mid to atrocious after-sales support. If this doesn't deter you, then go ahead and get one.

I do a lot of my functional parts in ABS, ASA though printing such material may be difficult on an open-air machine. The two obvious choices will generally be PLA or PETG. PLA is one of the most common printed materials, and is fairly balanced in material strength. PETG parts are more likely to permanently deform heavily before fully snapping, as well as they have a but more temperature resistance than PLA. Additionally most PETG plastics hold up decently well to UV, often making them more suitable for parts that need to be outdoors.

PLA takes not much consideration on surface to print, as most printers come with a smooth PEI build sheet by default. It will however need more cooling than printing with PETG at equivalent speeds. If you use a PEI sheet for PETG, make sure it is textured. You will destroy a smooth sheet if it doesn't have some kind of release coating to lower its adhesive properties to PETG.

There is no guarantee for spools of filament to actually arrive dry, so a filament dryer isn't a bad idea. I don't have any particular recommendations for a good filament dryer. I have a Filadryer S2 from Sunlu, but am not impressed by it.

Great choice; I personally found the A1 Mini to be an excellent starter machine.

Start off with a few spools of PLA in a few different colors. It's easy enough to buy whatever you need on Amazon.

I live in a moist climate and haven't yet bothered with a dryer, but I also haven't messed with TPU yet.

Yup, all the Bambu printers are pretty good. I'm quite happy with my P1S + AMS. Definitely a better choice for a beginner than the Enders and similarly cheap project printers that many people start out with.

You can always buy an AMS later if you don't want to now, but the utility of it for me is more around having multiple filaments to choose from without having to load a new filament rather than multicolour printing which is very slow and wasteful.

I wouldn't bother with a filament dryer. I live in a pretty humid climate and between work and home I've been 3D printing things for over a decade and have never felt the need to dry my filament. I'd only really consider it if I was starting to print Nylon or something similarly hygroscopic.

You got a few good replies, but I just want to briefly mention build volume. Nearly everything I print is functional. Splitting prints into sections isn't the biggest deal, but being able to print things in one shot is nice. Consider the size of things you'll be printing and ask if you think you'll be happy.

Do you have a cat/dog/platypus/other ? Buy a P1S