Though Tyson never wants to get married, he would happily get engaged to someone he really cared about and he does have a tendency to go above and beyond with romantic gestures.
When it comes to proposals, however, Tyson would likely be much more subdued. It would naturally depend on the person he was proposing to, but - with the most likely candidates having been Kim and Sebastian - it would be a safe bet to say that Tyson’s propose would be low key.
It certainly wouldn’t be going out to dinner, his anxiety is bad enough as it is, and definitely not a - completely - surprise proposal; talk of getting engaged in the future would have needed to be on the table first.
He would absolutely already have a ring on hand for this proposal, in his bag or pocket for months before he figured out exactly how to do it. With someone like Kim, who put a high value on craft and personal effort, Tyson would favour using one of his own metal gift boxes. With someone like Sebastian, who does care about skilled craftsmanship but puts a higher value on tradition, Tyson would use a normal ring box.
By the time he was ready to propose, Tyson would have a speech maybe thirty per cent written out and a general framework for a further twenty. Regardless of how much Tyson had figured out to say beforehand, it would all go out of the window once he started actually talking.
With Kimiko, Tyson would have likely opened by walking in, saying ‘catch’, and tossing the box over to her. Then after gauging the response, and likely getting a hopeful ‘yeah?’ and coy smile from Kim, Tyson would go down onto one knee and offer his proposal properly; and probably only get a few sentences in before she got impatient and just tackled him into a hug.
With Sebastian, Tyson would make more of an effort towards doing things more traditionally. He would take him out stargazing somewhere, having Sebastian sit on a rock whilst Tyson sat on the ground leant against his legs like he normally would. Then he could easily turn around to be knelt on one knee, and balance the box on Sebastian’s knee.