if you're getting a soprano uke you might find you don't need a strap - wait and see how you get on with the uke before deciding, if you have problems holding the uke and playing then yeah get or make a strap (you can make something for a soprano easily with a bit of string, tie it round the waist of the uke, and round the headstock, there are vids on youtube showing how). some people don't use a strap for any uke, even baritones, i don't use a strap for sopranos or concert size ukes, and if you're mostly gonna be sitting down to play you're even less likely to need a strap.
i would recommend a tuner, clip on or other, but then i don't have a smart phone so if i had one and an app for that, i might not be saying this!
yes to a case or gigbag if you will be taking the uke out and about with you. or............... heaven forbid................ leaving it around your home unplayed for long periods!!
a stand is a good idea, it's easy to kick over, stand on, even sit on small ukes! a stand keeps the uke out and ready to play, but safe and steady
there are indeed lots of learning resources online including on youtube, but if you fancy the idea of going off grid occasionally you can't go wrong with the marvellous starter book "ukulele for dummies" it's informative and amusing. the author doesn't think baritones are much cop but apart from that i agree with everything he says!
when i started out on uke, i got a cheap painted soprano uke, £20, a clip on tuner, and "ukulele for dummies". i still play and love that uke! it came with a thin nylon... you can't really call it a gigbag, it was a cover really, very thin - once i realised how much i loved the uke, i got a hard case for it that cost more than the uke itself!
ah................................ uke love makes you do crazy things!!