Looking for feedback on our mortgage + investing plan (this works for us)!

My wife and I are in our early 30s and closing on our house on 12/31. We’ll have a $488k mortgage, 30 years at 6.875%, but our lender gives us a free refi for the next 3 years, so we’re hoping that rate comes down.

After all expenses and funding our Roth IRAs/401k, we should have around $3.5k left over each month (probably closer to $4.7k, but I’m sandbagging). No kids yet, but that will change in the next few years.

We’ll have about $130k in cash after closing. The plan is:
• Put $50k in a HYSA
• Keep $25k in our checking
• Invest $55k into VOO
• Then at the end of each year, anything above the $50k/$25k in HYSA / cash goes straight into VOO

The idea is to build that up for ~10 years and then throw a big lump sum at the mortgage to knock out a big chunk of it (or maybe even pay most of it off).

I know this isn’t the “perfect” strategy and some people might say to either invest everything or just focus on the mortgage, but does this sound reasonable? Anyone else taken this kind of hybrid approach? It keeps it simple and straightforward while having plenty for emergency but also building up in something “safe”.