If you're playing at the table, physical props go a long way to set the mood. Here is a simple list of props to consider for your game.
The official OSR+ Character Creator works on tablets and mobile devices, so whether you've got one of those or your laptop at the table, you'll be able to interact with your character sheet without needing pen and paper.
The Character Creator also allows you to download an editable PDF that you can print out if you desire. In the Core Rules, you'll At the time of this revision, printed character sheets do not exist for OSR+, but they're in the works! find a printable template for character sheets if you want to do things the old fashioned way and write everything out by hand.
Handouts & Objects
Printed handouts and props (like tokens, playing cards, or representational objects) enhance immersion by giving players something to engage with in the physical space. You could, for example, manage gold with actual tokens, or manage supply with a deck of playing cards.
You can provide visual art (for example, portraits of NPCs), but keep in mind that the more you depict on behalf of your players, the less they will rely on the theater of mind to fill in the blanks. If the game you're playing is horror-themed, for example, it might be better to avoid visual aids of any kind, as the players will often imagine things far more terrifying than anything you could depict!
OSR+ requires only a single d6 to play, though having two d6 per player is advisable to make rolling for advantage and disadvantage easier. That being said, it's a lot easier for everyone to have a full set of dice available, especially if you want to roll for arbitrary random ranges as a GM.
You can find physical dice just about anywhere. Amazon has a lot of cheap sets. Also consider visiting your local game store, or an RPG convention to find more exotic polyhedrons.
A GM screen is a small, 10"-high trifold designed to be plastered with rules tables that the GM can use to roll dice behind. It serves both as a quick reference guide for the GM, and a privacy shield to protect players from seeing your dice rolls.
I personally don’t recommend you shield your dice rolls, however.
Minis are a staple of traditional RPGs, and although OSR+ does not require a grid to lay out combat encounters thanks to the use of abstract encounter spaces, it doesn't hurt to help visualize the battle by breaking out a vinyl hex map or grid. The kind that work with erasable markers are a must-have.
If you want to get really DIY, resin 3D printers such as the Anycubic Mono or the Elegoo Mars are consumer-ready. Coupled with HeroForge (a platform that provides the 3D STL files necessary to print custom minis), you can print your own minis exactly to your specifications.
Projectors & Monitors
If you have the table or wall space, a mounted or portable projector or external monitor can create a whole new level of immersion for your players. You can use a projector connected to a laptop to display the world map or other visual aids that would ordinarily be easy to share in a remote, digital environment.