Am I ready to submit my visa application for Taiwan with the provided documents?

You should add more documentation to support your application under the "workcation" category...

(or prepare for a request to submit additional documentation).

I suggest you add this merged together (incl. your Upwork profile):

- COVER LETTER (Key points: self employed freelancer, work description, that all your work is done remote, foreign clients and your interest in working remotely from Thailand)

- PORTFOLIO (presentation/summary of your skills and the services/work you offer in your role as a freelancer, examples of your previous work plus a screenshot of and link to your Upwork profile)

- CONTRACTS/PAYMENTS (client contracts, Upwork Earning Certificate, proof of payments, i.e. invoices and bank transfers from clients OR upwork payments and bank statements with payments highlighted)

WHAT ELSE TO OTHER BRING AND/OR PREPARE

- Passport

- Digital photo to upload (not older than 6 month)

- Home address (in your home country or country of residence)

- Address/current location (the hotel booking in Taipei)

- Certificate of Entry and Exit Dates (from the National Immigration Agency, NIA)

- Flight to Thailand, intended date and flight number

- Hotel booking or rental contract in Thailand

...and of course the bank statement you already mentioned.

Good luck!

Is the Upwork profile just to show past work? Maybe some evidence of current continuing contracts with clients, to show that you will continue earning money, would strengthen your application.

I think Taiwan asks you to go to their Immigration Department to get a certificate once you are there. Have a search in recent posts in this group about it