AIBU to struggle with having to hide my genuine opinions about colleagues at work?

Op cannot police what this other woman talks about at work. Including her “messy desk”. She can ask her not to comment but she can’t force her. That is life.

I’m in the same boat OP but I think you just have to get on with it. Some people can be very annoying though I think it helps to bear in mind that others may find us annoying too. Personally I have never felt any need to be friendly with work colleagues unless we genuinely are friends. But it is extremely important to be respectful and polite and professional in working relationships, how would team working and collaboration be possible otherwise? So I do pass a minute or two every morning chatting to my verbally incontinent work neighbour though I don’t give two hoots about her pets or tv viewing habits. I help a few people on the team with various work issues throughout the day as being 59 I’ve seen most of it before and so can. It’s just a necessary part of working life and I figure that doing all this helps me continue to receive a salary. I rarely dislike people though, I just view them as different. Practically I take regular short breaks from the team, walking round the office (which is huge) a few times a day and always taking a longer break at lunchtime, when I leave the office for a walk or meet friends. Over my career I have once moved teams to avoid a person, though I said I was looking for a sideways move to further my experience. I’ve also been honest and asked to move desks to avoid sitting next to someone who wore strong perfume that gave me headaches, but that was OK because at the time I had a manager I trusted. So I suppose what I’m saying is be strategic and adopt clear ways to make office life comfortable for you.

Most people find this hard, I think.

I've never found a solution -- other than to remember that I am being paid for being there, and part of the job I'm paid for is to perform an appropriate work persona.

Your "authentic self" sounds pretty judgemental TBH.

I'm not autistic but I do find lots of people annoying and don't much enjoy small talk with them. But I frame it as a requirement of my job: part of what I'm being paid for is having good working relationships. So that means it's my job roll to nod and say blandly, "that's interesting."

There are some relationships for which honesty and authenticity are key - like romantic partners. There are some where civility is more important. Would it help you to categorize people and connections into one or the other?

That said, I would have some ready phrases you can default to:
"Sorry I can't chat now, I'm on a deadline"
"I don't really know much about x"
"Oh, I'm not the person to ask about handbags/whatever"
Which is to say, you don't have to pretend to be interested. It's not a split being feigning loads of interest Vs being rude - you're trying to convey polite uninterest, in the way you might decline a food item you don't like: "not for me, thanks."

AIBU to find this aspect of working life so frustrating? And what practical strategies would you recommend?

Keep your head down and get on with your job.

Stop overthinking.

Remember it's possible that she really dislikes you too.

It's not the same, because OP is not making comments to this woman but this women is commenting to OP.

Pretending it's equal doesn't help the OP, does it?

And yes, NT do not bring their “authentic self’ to work. I filter what I say ALL THE TIME!

The way to manage this is to tell her her comments are upsetting you and making you sad (e.g.. when she comment on your desk).

This way it puts the onus on her to manage her behaviour.

She finds you messy, you find her materialistic. Live and let live. Do your job and go home. Polite is fine.

Very few people bring their authentic self to work.

most people have at least one colleague that they don’t get on with.

being professional - maintaining working relationship without telling them you hate them.

if you hate all of them look for a new job.

For the messy desk thing it is ok to say "I find it rude when you make those remarks, please don't".

For the bags thing, in the past I have said "wow that's a whole month's rent for a lot of people!" like in a tone of value neutral wonderment and it shuts them up.

She won't love you for either but then you don't like her anyway.

Why can’t you tell her to simply stop commenting on your desk and zone out and ignore her when she talks about designer stuff?

Can't you just get your head down, do your job and go home? Presumably you've got friends outside work that you socialise with so don't need new friends.

Pretending to be interesting and asking "how was your week-end" etc is par for the course in the work environment unfortunately, so yes, you are expected to do this a bit. If exchanging bland pleasantries isn't for you then perhaps office working with a team isn't for you either. Have you considered going self employed?