Howdy! Apologies in advance for the long-winded post. I'll break it down into sections so you can choose to skip to the main questions I want to ask:

Caveat:
I am very much not a professional and realize that probably the best thing for my floors is to contact a reputable professional to do this work for me. But I also like to consider myself pretty handy and able to learn techniques and principles quick enough that I can be comfortable doing this kind of work myself. Note "can be" -- I would like some advice to give me a bit more confidence before proceeding with my current project.

Current Situation:

I have had a contractor do self-level concrete install, and glue-down install of hardwood flooring in a couple bedrooms of my rickety old New Mexico house.

I'm a bit skeptical of the general contractor involved at this point for the following reasons:

initially the agreement was that the flooring would be a floating install. However, once the actual flooring subcontractor arrived to begin doing the install, he noted an unacceptable amount of lateral play in the floorboards. Because of this he recommended that we discard the floating underlayment I had bought, buy some glue, and glue the floor down instead

i always have to call the general contractor multiple times to discuss the same issue

he never remembers details of my project (multiple times when talking to him he thought that i was having laminate rather than engineered hardwood installed)

he doesn't follow through he said he would pick up and deliver my flooring for me for $70 but I actually had to pay closer to $300 to have it delivered by the flooring store)

Anyway, all of that is to explain why I now prefer to proceed with the rest of my install without the contractor's involvement.

Next Step:
The next step in my mind is to re-coat the engineered hardwood floor. For reference, this is the flooring I have installed: https://www.flooranddecor.com/engineere ... 27757.html

This floor does come with an Aluminum Oxide finish. However, there are a few reasons I believe it is a good idea to re-coat it right away:

that there are seams between the boards that would make some kinds of cleanup particularly difficult: i have a cat that pukes often; my friend who comes over regularly has a dog that isn't properly house trained (i'm okay with cleaning up dog pee, i just don't want it to accumulate in grooves)

I am also somewhat prone to spilling water occasionally and I would like to keep a dog water dish the room that will become my home office

The floor has an HDF core, which I suspect will be susceptible to water damage in the abovementioned scenarios and, of course, i just don't want dried cat puke accumulating between boards in the seams.

My intent is to use the Bona Traffic Naturale matte two part finish to preserve the color of my floors without giving them a shiny surface and protect them from scratches and liquid spills and stains.

I have been watching tutorials and troubleshooting videos related to finishing floors from the BonaProfessional channel

My Questions:

Do I need to use a sealer before applying the finish on a new floor that's pre-finished with Aluminum Oxide? Or is it fine just to recoat them purely with finish? The reason I ask is because I thought it might be good to "seal" the grooves between boards but I'm not sure how well a sealer will bond to the existing aluminum oxide finish.

Is it strictly necessary to sand or abrade the surface before applying the finish? If it is, is there a recommended process for doing so? I have been reading up on the use of Bona Prep for this, but it seems like that might be meant for floors that already have wear and tear whereas mine are fairly new.

I'll probably try applying the finish to a small section of one of the bedroom closets today just to see how it turns out (using the shallow x adhesion test described here) without additional prep. If that works out, i'd appreciate if anyone can recommend how to deal effectively with transitions between that small test section and the rest of the floor.

Thanks in advance for any advice or recommendations!

I'm continuing to read up and watch tutorial videos. Currently I'm leaning toward renting a floor buffer and following the Bona Prep instructions to:

* buffer with Bona Prep (which should soften the existing finish)
* abrade using 240 grit diamond pads
* vacuum thoroughly
* wet-tack with bona prep and a bona microfiber wet cleaning pad

Before recoating with the new finish. I'm pretty sure at this point that I don't need the sealer.

Only major uncertainty I have at this point is what kind of floor buffer I should rent...

Where ever you get the diamond discs may have a recommendation on type of buffer to use. A rental place will usually have 16 inch buffers. They may sell the diamond pads.I have never used diamond pads. I use abrasive screens, between coats, but I use a different process for prep on pre-finished flooring. It is a chemical prep, and coat by Basic Coatings.There is no scratching of the surface necessary for the process using the Tykote process.